Swimming Science: Optimizing Training and Performance 9780226287980

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swimming science Line weights.. CH1_SP2_G2

swimming science Edited by G . J o h n M u l l e n

optimizing training and performance

THE UNIVERSITY OF C HICAGO PRESS

The University of Chicago Press, Chicago 60637 © 2018 by Quarto Publishing plc All rights reserved. No part of this book may be used or reproduced in any manner whatsoever without written permission, except in the case of brief quotations in critical articles and reviews. For more information, contact the University of Chicago Press, 1427 E. 60th St., Chicago, IL 60637. Published 2018 Printed in China 27 26 25 24 23 22 21 20 19 18

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ISBN-13: 978-0-226-28784-3 (cloth) ISBN-13: 978-0-226-28798-0 (e-book) DOI: https://doi.org/10.7208/chicago/9780226287980.001.0001 Library of Congress Cataloging-in-Publication Data Names: Mullen, G. John, editor. Title: Swimming science : optimizing training and performance / edited by G. John Mullen. Description: Chicago : The University of Chicago Press, 2018. | Includes bibliographical references and index. Identifiers: LCCN 2017047739 | ISBN 9780226287843 (cloth : alk. paper) | ISBN 9780226287980 (e-book) Subjects: LCSH: Swimming—Training. Classification: LCC GV837.7 .S94 2018 | DDC 797.2/1—dc23 LC record available at https://lccn.loc.gov/2017047739 This book was conceived, designed, and produced by Ivy Press An imprint of The Quarto Group The Old Brewery 6 Blundell Street London N7 9BH United Kingdom T (0)20 7700 6700 F (0)20 7700 8066 www.QuartoKnows.com Publisher Susan Kelly Creative Director Michael Whitehead Editorial Director Tom Kitch Art Director James Lawrence Commissioning Editor Jacqui Sayers Senior Project Editor Caroline Earle Design JC Lanaway Illustrators Nick Rowland and Rob Brandt Copy Editor Gina Walker Note from the publisher Information given in this book is not intended to be taken as a replacement for medical advice. Any person with a condition requiring medical attention should consult a qualified medical practitioner or therapist. Cover image Getty images/simonk

Contents

I Introduction



C HAPTE R ON E



C HAPTE R TW O

8

h ydrodynamics

12

technique

40

p ool training

68

d ryland training

96

Tiago M. Barbosa

Rod Havriluk



C HAPTE R THRE E

Rod Havriluk



C HAPTE R FOUR

Allan Phillips



C HAPTE R FI V E

n utrition

124

injury prevention and rehabilitation

152

Kevin Iwasa-Madge



C HAPTE R S I X

G. John Mullen

APPENDICES Notes Glossary Notes on contributors Index Table of measurements Acknowledgments

180 185 189 190 192 192

Introduction

Swimming is a popular sport for people of all ages. Children are often first exposed when they learn to swim for safety, perhaps starting with splashing and then doing turns and tumbles, enjoying the feeling of weightlessness and the novelty of being in water. In fact, swimming is a truly unnatural activity for humans, requiring swimmers to be instructed from their first stroke. Unlike any other sport, swimming requires athletes to move as rapidly as possible through a medium more dense than air. The density of water makes the precision of every action important, as the additional resistance of an improper action greatly reduces swimming velocity. Understanding the science behind swimming therefore enhances both proficiency and enjoyment in the sport. Since appearing in the 1896 Olympics, competitive swimming has seen vast changes in style, form, attire, and location. At first, swimming events were held in open water, before switching to the pool in 1908. Male competitors wore full-body swim suits up until the 1940s, and the nature of fabrics available at the time meant this significantly increased the drag on the swimmer. Lane markers were not used before 1924 and starts weren’t incorporated until 1936. Swimming goggles were not allowed until as late as 1976. From across the globe, Swimming Science brings you the insights of leading experts in physical, mental, technical, and tactical aspects of the sport. This book binds together their significant findings with those of scientists who have parsed and studied every element of swimming, most notably the original swimming scientist, Doc Counsilman. Some discoveries were made in the nineteenth century and others as recently as this year. A wide range of sciences is embraced here, as swimming involves a surprisingly diverse array of disciplines. For example, at different stages of his career, Michael Phelps—arguably the greatest male swimmer of all time—has relied on various aspects of science to hone his swimming to ever more impressive levels. His technical skills, strong work ethic, and training base were developed as a young swimmer in Baltimore,

8

Introduction

a With the help of advanced swimming science Michael Phelps became the most decorated Olympian of all-time.

Maryland. He has subsequently concentrated on physical preparation—a key factor in his relatively injury-free career—and has cultivated a mental toughness that has been severely tested under daunting pressure to win multiple gold medals, resulting in amazing race finishes with Milorad Cavic. Each chapter in this book deals with a different scientific discipline, providing the reader with the background to better understand the sport. A single solution doesn’t work for every swimmer, so instead of offering a panacea or list of drills, the authors present science-based approaches that enable one to tailor solutions to individual situations. Chapter 1, Hydrodynamics, breaks down how the water interacts with the body during swimming. Understanding how to stay streamlined in the water and how various joint positions create torque and power is essential in the sport. The biomechanics of effective swimming strokes are dealt with in Chapter 2, Technique. Unlike in other sports, technique is the greatest contributor to success in swimming, yet remains the area requiring most improvement, for the majority of swimmers. Some aspects of technique are not included due to space limitations, such as kicking, breaststroke timing, freestyle and butterfly arm recovery, backstroke finishes, relay take-offs, and

10

Introduction

turns. Chapter 3, Training, discusses the physiological demands of swimming and how training influences swimmers’ ability to deal with these. Competitive swimming today requires a very high level of physical performance, so Chapter 4, Dryland Training, delves into the science behind improving fitness and strength through training outside of the pool. Chapter 5, Nutrition, considers the optimal proportions of different foods and fluids for swimmers to consume, to regenerate the body for maximum performance. The sport’s heavy physical demands can lead to injury, so Chapter 6, Injury Prevention and Rehabilitation, addresses the best ways of preventing or minimizing the risks of tissue damage. Finally, each chapter includes a detailed look at how specialized equipment—such as that used in computer fluid dynamics, kinematics, and electromyography—has impacted swimming science, and the photographic Science in Action pages show how the professional sport has benefited directly from the application of scientific principles.

g d Graphically speaking This book will introduce you to the science that has developed over many years of swimming practice, from the fundamentals of hydrodynamics and body biomechanics to the latest developments in swimming technology.

Whether you dip into the book for answers to specific questions or read it straight through for an overview, Swimming Science reveals the science at work when swimmer meets water.

11

Hydrodynamics play a significant role in the swimmer’s performance. This chapter provides insight into how the water interacts with the swimmer and the forces acting upon the body. It examines the way water flows around the swimmer and how the forces produced can have an impact on the energy expended during swimming, and hence on the swimming efficiency. Swimmers, coaches, and researchers spend a good deal of time trying to understand how to optimize these key aspects. Cutting-edge devices are used to assess the swimmers, making them more efficient and improving their performance. These assessments can encompass the way the body is aligned, swimwear, or small details such as the position of the fingers during swimming.

chapter one

hydrodynamics Tiago M. Barbosa

What is the free body diagram of a swimmer?

What are the forces acting on me when I swim?

To have a deeper understanding of the swimmer’s hydrodynamics we need to learn what the main forces acting upon the body are and how they interplay. Ultimately, swimming acceleration and speed depend on propulsive forces, resistive forces, and inertial parameters. Propulsive forces are those related to the thrust and forward movement. Resistive forces act opposite to the swimmer’s direction of displacement. The inertial parameters are related to body features (anthropometric characteristics). Thrust is due to steady and unsteady flow patterns (see pages 16–17), and is the sum of propulsive drag, lift force, and the jet vortex (see pages 28–29). The resistive force is also known as total drag force and results from three components—friction drag, pressure drag, and wave drag. Regarding the inertial parameters, these include the swimmer’s body mass and the added mass of water.

a Free body

This free body diagram shows the applied forces acting on a swimmer’s body while moving through the water at a steady speed. The lengths of the arrows are proportional to their magnitudes. Here, the forward thrust Fthrust and backward drag Fdrag are equal in magnitude, so there is no net force acting to accelerate the swimmer. The upward force Fup is a combination of buoyancy and lift resulting from the swimmer’s motion through the water. It is equal and opposite to the downward force Fmass, which is the swimmer’s weight.

14

Hydrodynamics

Fdrag

Based on these external forces it is possible to model the swimming stroke and make a rough estimation of the acceleration-time and speed-time curves within the stroke cycle (see pages 32–33). The swimmer does not move at a constant speed—that is, with uniform motion. Instead, over a stroke cycle, there are positive and negative accelerations. The typical profile of these curves depends on the swimming stroke, but in general positive accelerations occur when the thrust is greater than the drag force—for instance, during the pull phase. On the other hand, acceleration is negative when the thrust is smaller than the drag force—for example, during the arm’s recovery. Therefore, one can swim faster by increasing the thrust while keeping the drag constant, by keeping the thrust constant and decreasing the drag, or by both increasing the thrust and simultaneously decreasing the drag force.

Forces and inertia Thrust

Drag force

Inertial parameters

Fthrust

Fdrag

Thrust (positive force, acting in forward direction) is the sum of several forces produced by the swimmer, based on steady or unsteady flows. These are propulsive drag (caused by pulling the hand directly backward), lift forces (caused by sculling actions of the hands) and the jet vortex effect, besides others. Thrust is produced by both upper and lower limbs.

Drag force (negative force, acting backward) results from the collision between the swimmer and the water molecules, and is one of the main concerns for support staff (sport analysts), coaches and swimmers. The total drag force can be broken down into three main components—friction drag (or viscous drag), pressure drag (also known as form or profile drag), and wave drag. A great deal of effort has been made over the decades to understand the role of drag in swimming and how to minimize its effects. This can be achieved by improving swimming technique, designing new swimming apparel (such as swim suits, caps, goggles) and building pools with different specifications of depth and width.

The two main inertial parameters are the body’s mass and the added mass of water.

Fup

Even though the surfaces of the feet and hands are the most important, there is evidence that the forearm, upper arm, shank, and thigh may also contribute to the production of propulsive drag, at least in some phases of the stroke cycle.1,2

A body’s inertial mass is a measure of its resistance to changes in velocity—that is, to being accelerated. There is an inverse relationship between acceleration and mass according to Newton’s second law, F = m × a. Hence, the larger the mass m of the swimmer, the smaller the acceleration a for the same mechanical force F. The mechanical force F is the sum of the thrust F thrust and drag Fdrag. Total inertial mass is the sum of the swimmer’s mass plus the added water mass. When a body moves in water, it effectively drags some surrounding water with it. As a percentage of body mass, the added mass is roughly 24% for women and 27% for men.3 Newton’s second law equation becomes F = (m + m added) × a. The heavier the subject, the more added mass will be carried, compounding the inverse effect on acceleration.

Fthrust

Fmass 15

What is the influence of water flow on a swimmer’s displacement? Water, like any fluid, is a substance that flows and deforms when forces are applied to it. The way water flows around a swimmer affects several forces that act on the body, including the thrust (see pages 28–29) and the resistance (see pages 18–19). Fluids, such as water, are characterized by a set of properties. The most important are the density (mass or quantity of matter per unit of volume), and the viscosity (resistance to the movement of particles in the flowing substance). The flow can be steady or unsteady. A flow is characterized as steady when there are no changes in the fluid velocity and pressure at a given point of the body over time. Conversely, if these properties change, the flow is unsteady. Both steady and unsteady flows play determinant roles in the production of thrust.1

Line weights..

CH1_SP2_G3_A

If the swimmer’s limbs are moving at a constant or almost constant speed, with no significant changes in direction, then the water properties do not change over time and conditions are steady. Under these conditions, there are two propulsive forces, which are the drag and the lift produced by the hands and feet, whose speed and orientation are constant (see pages 28–29).

How does water surround me as I swim? On the other hand, when the swimmer’s hands or feet accelerate or change direction suddenly, unsteady flows are created and this produces thrust. The speeds of the hands and the feet increase over their underwater trajectories. The hands accelerate from their entry into the water to their exit, and the feet also undergo accelerations as they kick up and down. In analyzing these unsteady conditions, we can assess the water circulation around the body or the limbs and observe, for instance, the generation of vortices. Flow can also be described as laminar or turbulent. The flow is laminar when the layers of fluid are well organized and parallel to the swimmer’s body. If the water layers show a random organization then this is turbulent flow.

d Let it flow When the layers of fluid are parallel and well organized with no disturbance, the flow is said to be laminar. The velocity and pressure at each point are constant, and the water around the body appears smooth. Laminar flow happens typically at slow swim speeds—for instance, when gliding in the streamlined position at a relatively low speed (A). At higher speeds, the water surrounding the body appears increasingly erratic, and swirling masses called eddies are observed, notably on the body edges. The water layers are no longer parallel—the flow is becoming turbulent (B). The resistance drag in turbulent flow is significantly higher than in laminar flow, so swimmers try to minimize turbulent flow as much as possible.

CH1_SP2_G3_B

Laminar and turbulent flow

A

B

16

Hydrodynamics

CH1_SP2_G1_Af

Flow analysis

CH1_SP2_G1_Cf

CH1_SP2_G1_Bf

a Steady as you go

We can visualize steady and unsteady flows using threads, or tufts, attached to the body (right).2 The swimming stroke is recorded on video and the tufts’ orientation inspected frame-by-frame. In this way, changes in a limb’s velocity and direction can be observed over the course of the stroke. Extreme changes in the tufts’ orientation from one frame to the next suggest that the flow direction changed suddenly. The arrows in the diagrams represent the speed and direction of movement of the hand, elbow and shoulder. Air bubbles or dye can also be injected into the water, and used for qualitative analysis of flow (below).3 Here, a swimmer is performing dolphin kicks. Each time the feet change from upward to downward movement, or downward to upward, there is a cluster of air bubbles. This allows us to weights.. observe the water circulation and vortices due to theLine sudden change of CH1_SP2_G2 direction of the accelerated limb.

CH1_SP2_G1_As

CH1_SP2_G1_Bs CH1_SP2_G1_Cs

Speed and direction of hand Speed and direction of elbow Speed and direction of shoulder

speed and direction of hand speed and direction of elbow CH1_SP2_G1_KEY speed and direction of shoulder speed and direction of hand speed and direction of elbow speed and direction of shoulder speed and direction of hand speed and direction of elbow speed and direction of shoulder

CH1_SP2_G1_KEY CH1_SP2_G1_KEY

Reynolds number To assess how laminar or turbulent the flow is, we can calculate the Reynolds number. This is a number that takes into account the water density, velocity, body length, and viscosity: Reynolds number

=

density × velocity × length viscosity

A young swimmer around 12 years old has a Reynolds number of about 2,500,000 at top speed.4 For the men’s 50 m freestyle world record holder, who is taller and faster, the Reynolds number is much higher, at around 5,200,000. There is a critical Reynolds number value at which flow becomes turbulent. This depends on body shape but, as rule of thumb, flow becomes turbulent at about 500,000. In swimming, the transition from laminar to turbulent flow occurs somewhere between 500,000 and 10 million, so the flow surrounding a racing swimmer cannot be considered to be laminar.5

Variations across species

Blue whale

Bacterium 10-5

Human

Small fish 10-4

10-3

10-2

10-1

1

10

102

103

104

105

106

107

108

109

Reynolds number Large fish

Dolphin

Graphics not to scale

17

How does drag force affect swimmers?

How does water resistance affect how I swim?

When an object moves through a real fluid such as water, which has viscosity and compressibility, there is always some resistance to overcome. This resistance is known as drag, because the object drags fluid particles along as it moves. Drag forces acting upon the body are a major concern because they slow us down, and can significantly affect performance. The magnitude of the drag depends on a set of variables. The higher the fluid’s density, the higher the drag, and this partly explains differences in salt water and fresh water performances. Water is about 800 times more dense than air, which means drag impacts a swimmer far more. Body surface also affects drag on a swimmer—the larger the area presented, the greater the drag. But the top determinant is the relative velocity between the body and the water—the faster you go, the more resistance there is to overcome. Drag forces can be broken down into three different components—skin friction drag (or viscous drag), pressure drag (or form drag), and wave-making drag.1

Wave-making drag reflects the energy needed to push the water out of the way in swimming. As the body moves forward, fluid tends to “pile up” at the front, while “hollows” are produced in the rear, creating waves. Wave making decreases swimming efficiency in two ways—first, it takes energy that could have been used for forward movement, and second, waves reflected from the pool walls collide with the swimmer, transferring momentum and impeding performance.

d Total drag The total drag on a swimmer D is the sum of the three components skin friction drag Df , pressure drag Dp, and wave-making drag Dw. That is, D = Df + Dp + Dw. Skin friction drag is directly proportional to swim velocity v, so it increases as the swimmer gets faster in a 1:1 relation. However, pressure drag is proportional to v2, and wave-making drag is proportional to v3, so these components increase very steeply indeed with swim velocity.2,3 Pressure drag and wave-making drag in particular are extremely sensitive to changes in body position, and so—because these factors increase so drastically at greater speeds—the faster the swimmer goes, the more critical good technique becomes.

Skin friction drag results from interaction between the water’s viscosity and the body’s surface. The water layer in contact with the skin sticks to it, and travels at the same speed as the body, so the relative speed is zero. This is the boundary layer. The next layer of water is decelerated by this layer, and so on, progressively further from the body. The higher the skin friction drag, the more water is dragged (or trailed) behind the body.

18

Hydrodynamics

Wave-making drag

Drag

Pressure drag is related to the pressure difference between the leading and trailing edges of the body. At the front, there is high pressure where fluid particles are compressed. Particles then flow around the body, and eventually separate from the body at the boundary layer separation point. Beyond this, the flow reverses, producing vortices and a low-pressure region. The pressure differential means particles tend to move from the front to the rear of the body, “pushing” it backward—that is, producing pressure drag opposing the direction of movement.

Drag forces acting on a swimmer

Pressure drag Skin friction drag Swim speed

Separation point Streamlined form—smaller pressure drag Boundary layer separation occurs further back

Turbulent flow

Laminar flow

Smaller wake of fluid dragged behind body Lower pressure

Higher pressure

Smaller pressure differential

Unstreamlined form—greater pressure drag

Boundary layer separation occurs further forward Turbulent flow Vortices

Laminar flow

Lower pressure Larger wake of fluid dragged behind body

Larger pressure differential

NEED TO KNOW Total drag on a swimmer, D = ½ ρ v2 A Cd where ρ is the water density, v is the velocity of the swimmer’s body relative to the water, A is the projected frontal area of the swimmer’s body, and Cd is a dimensionless variable (it has no units) called the drag coefficient. Because the total drag is the product of density, velocity, area and drag coefficient multiplied together, we can see that if any of these variables increases then the total drag will be greater. Of these, swimming velocity is the top determinant of drag for a swimmer, since the drag increases in proportion to v2.

Higher pressure

o Pressure effects If there were no boundary layer separation point, the pressures at the front and rear of the body would be equal and hence the pressure drag would be zero. The closer the separation point gets to the front of the body, the greater the pressure differential and therefore the pressure drag will be. This means that the swimmer’s position in the water significantly affects the pressure drag—a very well-streamlined position allows the separation point to occur closer to the rear (top image). However, a poorly streamlined position, with limbs misaligned, causes the separation point to be further forward, which much increases the resistance (bottom image).

19

equipment: computational fluid dynamics Computational fluid dynamics (CFD) is a cutting-edge technique used to model a swimmer’s hydrodynamics. It has origins in the aerospace industry, and was only applied in sports, notably in competitive swimming, during the late 1990s and early 2000s. Medicine, architecture, automobile design, and biology are other fields that frequently use computational fluid dynamics. CFD allows us to visualize how fluid (air or water) flows around a body, and to quantify key parameters such as drag and propulsive forces. The technique uses numerical analysis and a set of algorithms to solve problems related to water flow, which can help swimmers improve their performance by understanding the effects of changing body position, for example, or of using different garments (swimwear, goggles, caps). For instance, CFD can be used to model the effects of different finger positions on thrust, or of different swim suit designs on the drag force.

There are three main steps involved in performing an analysis using CFD. During pre-processing, relevant data is collected and prepared. Once these data are entered as a set of inputs, then the simulation is run. Because of the complexity of the calculations, the simulation is run on dedicated software. Finally, during post-processing, the output of the simulation is retrieved. For a given set of inputs, the output will be always the same. But if we slightly change one or several inputs, the output changes accordingly, modeling the effects of those inputs in a real-world system. A major advantage of CFD is that it is possible to test a wide variety of inputs, until the best result is reached, with no need of physical experimentation or testing. So instead of inviting a swimmer to perform several trials in the pool under different conditions, we can simulate the effects in silico—that is, using software. Swimming performance depends on marginal changes in a given technique or characteristic. To investigate the effects of such small changes, CFD is more accurate than

CH1_SP3A_EQUIP_G3_LOWER_ARM

Flow simulation

a Showing the flow

Having imported the data and set the inputs, the next step is to run the calculations. The time required for this depends on the complexity of the model and domain, as well as the computational resources available—it can take from a few minutes to several hours. Once calculations are complete, the results are checked—if errors are found, the inputs should be adjusted and the simulation re-run. A visual representation like that shown here highlights the body’s geometry and the way the fluid flows around it.

20

Hydrodynamics

CH1_SP3A_EQUIP_G1 SCANNER

Collecting data

experimental testing, if properly conducted. The main drawback is that if the inputs are not specific and accurate enough the output will be less reliable. Hence, pre-processing is the step that takes most time—making sure the inputs are accurate increases the quality of the output. Another limitation of CFD is the cost involved, because of the huge computational resources needed to run the simulations.

CH1_SP3A_EQUIP_G1_TECHCOMP

g o Model subject In the initial pre-processing step, the swimmer’s body is scanned, either in part or as a whole. This generates the model body to be analyzed. Next, the domain is set. The domain is constructed from a mesh of millions of small tetrahedral cells and represents the volume of fluid through which the body is to move. Now the mathematical equations used to model the chosen conditions are selected. For example, specific algorithms can be used to model a certain orientation of the body in the domain, swimwear of a particular roughness, or a swim lane containing water of specific temperature, viscosity, density and turbulence. CH1_SP3A_EQUIP_G3_UPPER_ARM

Pressure drag analysis

a Color by numbers

CH1_SP3A_EQUIP_G3_UPPER_KEY

Visual inspection of the flow is a qualitative analysis. Besides that, it is also possible to retrieve quantitative data from CFD simulations, such as the magnitude of the drag or propulsive forces, and insights about the components that contribute to these. This graphic shows the pressure drag on the forearm and the hand—a warmer color denotes a higher pressure on the region, measured in pascals (Pa).

Pa smaller pressure drag

–8500 –7500 –6500 –5500 –4500 –3500 –2500 –1500

–500

500

1500

greater pressure drag

21

Is drafting beneficial during training, open water and triathlon competitions?

Why is it easier if I swim behind another swimmer? Optimal distance

Anyone who has swum a few laps in a pool trailing behind a fellow swimmer will have felt that the effort is less than swimming alone. This happens quite often in training settings in competitive swimming, but also in open water and triathlon events. The lower effort perceived when swimming behind someone is due to drafting effects. The aim of the drafting technique is to diminish the drag force. This happens when two or more swimmers are in a close group and fairly well aligned. Behind the leading swimmer, a region of slipstream is created, as the wake of water is displaced at a similar velocity to that of the swimmer. The slipstream region depends on the shape of the body—humans do not have a perfect hydrodynamic shape so the slipstream is rather big. The water flow over a swimmer’s body is typically turbulent (see pages 16–17), which means that the pressure in the slipstream region is lower than in the surrounding environment, creating a perceptible “suction effect.” Drafting involves a swimmer staying inside the slipstream region of a fellow swimmer in front. This is beneficial for both swimmers when moving at the same speed. Because the swimmer behind is inside a region of lower pressure in the slipstream (a “suction region”), he or she needs to expend much less energy and power to move forward.1 Wave drag may also be reduced in close-in drafting positions due to the decreased relative velocity of the disturbed flow close to the lead swimmer, which means smaller waves are created by the drafting swimmer.2 Drafting is also a benefit for the leading swimmer. As we saw on pages 18–19, pressure drag is due to the pressure difference between the leading and trailing edges of the swimmer’s body—a larger difference creates a greater pressure drag. When a swimmer is trailing behind the leading swimmer, the effect of the low-pressure region is reduced, and this therefore decreases the pressure drag on the leader.

22

0.55 yd (0.5 m)

3.3 yd (3.0 m)

5.5 yd (5.0 m) Cd ≈ 56% 6.6 yd (6.0 m)

Cd ≈ 65%

Cd ≈ 75%

Hydrodynamics

Cd ≈ 84%

CH1_SP4_G2_A Drafting and stroke efficiency

2

Side drafting

1.1 yd (1 m)

o Side by side

It’s also possible to reduce the drag coefficient by swimming beside another swimmer, although the reduction is only one third of the reported value achieved when directly behind the leader.2 The optimal position is about 1.1 yd (1 m) to the side and behind the leading swimmer, so that the drafter’s head is level with the leader’s hip.

Stroke length (m/stroke) Stroke length (m/stroke)

What is the optimal distance between swimmers to enhance the drafting effect? The drag coefficient of the trailing swimmer increases with distance, so that swimming 0.55 yd (0.5 m) behind another swimmer results in a relative drag coefficient Cd of about 56% of that of the leader, while a gap of 6.6 yd (6 m) means the back swimmer’s Cd is about 84% of the leader’s.4 Drafting at 0 yd (0 m) is no more beneficial than drafting at 0.6 yd (0.5 m)2—and in fact being very close can be a liability as visibility is impaired by bubbles and turbulence, and the possibility of hitting the feet of the leading swimmer affects arm stroke trajectory. Based on this evidence, the distance between swimmers should be more than 7.7 yd (7 m), so that all swimmers are under similar hydrodynamic conditions. In open water events and triathlons, swimmers should consider drafting when deciding race strategy, to help save energy.

1.45 1.45

1.40 1.4

CH1_SP4_G2_B

1.35 1.35 1.3 1.30

1.25 1.25

50 50

100 100

150 200 200 250 250 300 300 150 Swimdistance distance (m)(m) Swim

350 350

400 400

350 350

400 400

3.2 3.2 3.0 3.0

CH1_SP4_G2_C

2.8 2.8 2.6 2.6 2.4 2.4

50 50

100 100

150 200 200 250 250 300 300 150 Swimdistance distance (m)(m) Swim

2.25 2.25 2.15 2.15

CH1_SP4_G2_D

2.05 2.05 1.95 1.95 1.85 1.85

Stroke frequency Stroke frequency (strokes/min) (strokes/min)

g Keeping your distance

1.5 1.50

Stroke index—efficiency (m /s) Stroke lindex-efficiency

Does drafting affect the swimmer’s stroke? To assess the swim stroke, four parameters are often monitored: swim velocity, stroke frequency (or cadence), stroke length (or amplitude), and stroke index (a higher stroke index indicates more efficient swimming). A study comparing drafting and non-drafting swimmers did find differences in the stroke mechanics.3 When drafting, the swim speed, stroke length, and swimming efficiency (stroke index) were higher than when non-drafting by 3.5%, 4.7%, and 7.15%, respectively. The drafting swimmers kept a more even pace, and the stroke length and stroke index were enhanced too. Conversely, the stroke frequency showed no significant difference between conditions, especially in the last part of the swim distance. So, drafting appears to keep the stroke mechanics more consistent during an event or training session.

Stroke (m/s) Swimvelocity velocity (m/s)

a Different strokes

50 50

100 100

150 200 200 250 250 300 300 150 Swimdistance distance (m)(m) Swim

350 350

400 400

50 50

100 100

150 200 200 250 250 300 300 150 Swim distance (m) Swim distance (m)

350 350

400 400

44 44 42 42 40 40 38 38 36 26

NEED TO KNOW Stroke index (SI)—the stroke index is an overall index of swimming efficiency. SI = velocity × stroke length

Drafting Non-drafting Average for drafting Average for non-drafting

23

What is a swimmer’s hull speed?

What is the fastest I can swim?

Just like a boat, a swimmer moving over the surface pushes water out of the way. In doing so, the swimmer compresses the water particles and creates waves. Creating waves takes energy, which is not then available to propel the swimmer forward. So the swimmer is wasting energy that could instead be used for more efficient displacement. A wave has a crest (the highest point or peak) and a trough (the lowest, deepest point). The amplitude is the height of the wave, from the midpoint to a crest, and the wavelength is the distance between two consecutive crests. As swimming speed increases, the wavelength of the created waves also increases. At a certain speed, the wavelength is equal to the swimmer’s height or body length—this is known as the swimmer’s “hull speed.” Taller swimmers have a higher hull speed. Younger swimmers, because they are still growing, will increase their hull speed over time.1 Some researchers consider that, theoretically, the hull speed is the maximum speed that a swimmer can reach.2 Others, though, have reported elite swimmers displacing at speeds higher than their hull speed.3 In such cases, the swimmer is effectively swimming uphill to ride the wave.

So what are the relative benefits of swimming between two crests at the hull speed, or of riding up the wave? It seems that a pace enabling the swimmer to be between two wave crests is more economical. The swimmer is not repeatedly hitting the wave, and so is able to maintain a smooth and even pace. Sprinters, however, are willing to expend more energy to ride the wave, using some of the wave’s momentum to help them move forward. When this happens, wave drag drops significantly and the speed can increase substantially.4 Over a full freestyle swim stroke, the hull speed probably shows some slight variations.5 During the arm’s entry the “hull” of the swimmer is effectively longer because the arm is fully stretched in front. Moreover, as the arm enters the water it may smash the wave. However, once the arm is in the water, fully immersed and moving through its underwater path, the “hull” length corresponds to the swimmer’s height once again, and the head and shoulder immediately create a new wave.

d Riding the wave The hull speed is the speed at which the wavelength of the wave created by the swimmer is equal to the swimmer’s height or body length. On reaching the hull speed, the swimmer is “trapped” between the crests two waves (top). In order to exceed the hull velocity, the swimmer must swim “uphill” to climb the wave and ride it, which requires more energy (bottom).

Swimming at hull speed (wavelength = body length) Crest

Wavelength

Crest

Trough Amplitude

Body length 24

Hydrodynamics

Hull and race speed comparison Men’s 400 m freestyle

Men’s 50 m freestyle

Bronze medalist Vanderkaay 2% slower than hull speed

Bronze medalist Cielo 22% faster than hull speed

Silver medalist Park 2% faster than hull speed

Silver medalist Jones 20% faster than hull speed

Gold medalist Sun 0.1% slower than hull speed

Gold medalist Manaudou 21% faster than hull speed

o Energy economics Sprinters are not interested in being economical and saving energy. They want to be as fast as possible, and they spend as much energy per unit of time as necessary to achieve this. For long-distance and middle-distance swimmers, on the other hand, being economical is a key factor. Comparing the hull and race speeds of the medalists in the men’s 400 m freestyle at the London 2012 Olympics shows that both speeds are similar. For the men’s 50 m freestyle, however, the race speed is much higher than the hull speed. Florent Manaudou of France, who won gold in the men’s 50 m freestyle, and Sun Yang from China, who was the gold medalist in the men’s 400 m freestyle, are almost the same height—the French swimmer is 6 ft 6.3 in (1.99 m) tall and his Chinese counterpart is 6 ft 5.9 in (1.98 m). So, both have similar hull speeds. Nevertheless, Manaudou swam 21% faster than the hull speed, and Sun 0.1% slower.

Hull speed

Race speeds

NEED TO KNOW The hull speed formula hull speed =

gravitational acceleration × body length 6.283

Swimming faster than hull speed

25

SCIENCE

IN ACTION

swimwear

For more than a century, swimwear has been a major focus of interest, research, and development for competitive swimmers. In the 1890s, swimmers raced in wool swim suits covering the torso, part of the thighs, and the upper arms. Not until the 1936 Olympics were men allowed to compete in bare-chest suits, and men’s trunks became the norm only around 1948. The 1950s saw the introduction of nylon, and 30 years on, in the 1990s, manufacturers were able to produce suits made of polyester and elastane, with superior durability, elasticity, and drag properties. The trend for drag-reducing swimwear moved into new technological territories during the following decade, with suits made from non-textile materials in cuttingedge, body-length designs. These suits, made partially or totally of polyurethane, were tight fitting, compressing the body and reducing pressure drag. In addition, the seams were bonded and water repellent, which also decreased the friction drag. Some brands set panels in specific places in the suits to provide extra compression and optimize water flow around the body. By the late 2000s, these high-tech, performance-enhancing swim suits were hugely popular with top competitors, and in 2008 and 2009, many world records were broken. Then, amid concerns that such suits provided an unfair edge, they were abruptly banned in 2010 by the Fédération Internationale de Natation (FINA). Although high-tech suits were considered one of the best 50 inventions in 2008 by Time Magazine, critics argued that they should fall into the category of “technological doping.” Since 2010, swimmers must once again race in textile suits, and these must have no zipping device, and cover the body only from waist to knee in men and from shoulder to knee in women. Almost 130 world records were set in the high-tech era of 2008–2009, 50% of which still stood following the Olympic Games in Rio in 2016, two Olympic cycles after Beijing 2008.

26

Hydrodynamics

a Suited up

Michael Phelps of the USA and Paul Biedermann of Germany take the start of the men’s 200 m freestyle on 28 July 2009 at the FINA World Swimming Championships in Rome, wearing high-tech suits. Such suits could reportedly lower racing times by 2–4%.

What are the thrust mechanisms in swimming?

How do I propel myself in the water?

A swimmer’s displacement in the water depends on the relative magnitudes of the forward force, or thrust, and the drag force acting in the opposite direction (see pages 14–15). In order to generate thrust, the swimmer must produce movement in several body segments, notably the arm stroke of the upper limbs, and the kicking action of the legs. In freestyle, about 10–15% of the total body speed is due to the kicking motion, and the remaining 85–90% is attributed to the arm stroke.1 For the other competitive swim strokes, the relative contributions of upper and lower body movements are not yet clear, because of lack of research evidence. However, based on educated guesses, practitioners argue that the percentages will be roughly the same for backstroke and butterfly, with the contribution of the kicking action being much higher for breaststroke. Both upper (arm, forearm, and hand) and lower limbs produce thrust, by three main mechanisms—propulsive drag, lift force, and vortices. Propulsive drag is underpinned by Newton’s third law of motion, which states that for every action, there is an equal and opposite reaction. So when the water is pulled backward, as a reaction the body is propelled forward. That is why over the arm stroke the limbs rotate in the opposite direction to the body’s motion—the arms move backward so that the body moves forward. The larger the propulsive surface, the more water is displaced and hence the higher the magnitude of this force. Another factor is the arm’s speed— the faster the displacement the greater the force produced. If the arms moved in a straight line trajectory underwater, the propulsive drag would be the only force acting. However, elite swimmers perform a curved arm stroke in order to produce a second force—the lift. Each arm acts as a hydrofoil, which— because of the angle of attack resulting from the curved stroke—is able to produce lift.

28

Hydrodynamics

Vortices provide another source of thrust. A vortex is a rotating mass of fluid, shed backward when a limb suddenly changes direction, speed, or angle of attack, which results in a forward acceleration of the swimmer. This is why a swimmer should rapidly transition between up-down and down-up leg motion when kicking, for instance, and should accelerate the hand under the water from entry until exit.

NEED TO KNOW Hydrofoil A hydrofoil is a solid shape that produces a lift force larger than the drag force, when moving in water at a suitable angle. Because of the hydrofoil’s shape and angle of attack, water flowing over the top moves faster than water flowing over the lower surface, which creates lower pressure above than below. This pressure differential results in a lift force acting perpendicular to the water flow.

a Cut and thrust

Although there are alternative theories concerning the ways in which a swimmer’s forward thrust is generated, the current consensus among the scientific community is that propulsive drag, lift force, and vortices comprise the three main mechanisms.2,3 These are not exclusive to humans—other animals better adapted to the aquatic environment use the same strategies.4 The sum of the propulsive drag and lift produce the resultant force. Studies quantifying these forces have reported that in freestyle the propulsive drag reaches the peak value almost at the end of the underwater path (in a phase known as “upsweep”).5 This happens because in this phase the hand is moving upward, outward, and backward—hence, the propulsive drag has a downward, inward, and forward direction. The lift force acts perpendicular to the direction of water flow across the hand, from the higher to lower pressure zone (that is, from the palm to the back of the hand). So, the resultant of the two forces is in the direction of the displacement, and the effective forward propulsion is maximized.6

CH1_SP6_G3_CHART_C

Peak force

Resultant force Effective forward propulsive drag 0 0

11 22 33 44 55 66 77 88 99 Resultant force Effective forward propulsive force Frame during underwater path of freestyle arm stroke

10 10

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o Frame by frame This graph shows the changes in the resultant force (red line) and the effective forward propulsive drag (blue line) throughout the underwater path of the freestyle arm stroke.6 The stroke was video recorded, and the path analyzed frame by frame. At the beginning of the underwater path, a significant amount of resultant force is not used to produce effective forward propulsive drag (between frames 0 and 10). From the middle of the underwater path onward the hand adopts an orientation that maximizes the use of the resultant force. The peak force is reached by frame 16, toward the end of the underwater path.

Generating forward thrust

Lift force

Vortex propulsion

Water over the top surface flows over a shorter distance, so it has higher velocity and lower pressure. The pressure differential between the two sides of the hand results in a lift force.

Water over lower surface flows over a longer distance, so it has lower velocity and higher pressure.

16 16

Leading edge

Lift

Direction

Direction of hand movement

Propulsive drag

Trailing edge Drag

Resultant force

The hand acts as a hydrofoil

As the limb pushes back on the water, an equal and opposite force propels the body forward.

Angle of attack Right Hand

29

What is the effect of the hand’s surface area on thrust?

Should my fingers be spread out or closed?

The hands are one of the main sources of thrust in swimming. The hands and the arms are propulsive surfaces that act as paddles. Watching different elite swimmers racing reveals that they adopt a wide variety of finger and thumb positions as they push the water backward. Some swimmers keep their fingers close together, while others spread their fingers. The thumb may be adducted, positioned near to the remaining fingers, or abducted, with a slight gap between it and the index finger. So what is the best finger position to enhance the hand’s thrust? To investigate, an experimental test can be conducted using different models of hands, or subjects performing trials with the fingers in various positions, and the propulsive drag assessed.1 Alternatively, computational fluid dynamics simulations can be used (see pages 20–21), which are significantly more reliable.2 In experimental testing, even with consistent instruction, consecutive trials will yield slightly different results simply because of intra-individual variability. So, to study the marginal force changes produced with different finger positions, a numerical simulation may be the best option.

CH1 SP7 G2_A

Studies have shown that optimum finger position varies for different strokes, and during the arm’s motion. When water flows from finger tips to wrist, or in the opposite direction— for instance, during the hand’s entry and at the end of the underwater path in freestyle or butterfly—only trivial effects of the fingers’ relative positions are observed.3 There is a slightly higher thrust with the fingers grouped and thumb adducted. Conversely, if water flows from the thumb to the pinky finger (as during the “insweep” phase), the effect is more obvious— the best position is with thumb adducted and fingers slightly spread. When water flows from the pinky to the thumb (as during “upsweep”), having the thumb slightly abducted and the fingers grouped is best. This flow pattern happens, for instance, after the hand’s entry during backstroke. In an aircraft, wing flaps increase the lift force—for instance, during descent. Similarly in swimming, spreading the fingers and abducting the thumb increases the lift acting on the hand. While there isn’t one single best position for fingers and thumb, as a guideline the fingers should be grouped or slightly separated. The thumb should be adducted during water entry, water exit, and when the hand moves inward, but slightly abducted when moving outward. Hence, the fingers and thumb positions should change over the course of the swim stroke, depending on the water flow.

CH1 SP7 G2_B

Freestyle finger groupings

During the hand’s entry, fingers should be grouped and thumb adducted.

30

Hydrodynamics

When the hand is under his body (“insweep” phase) having the thumb adducted and the fingers slightly spread is the best option.

Fingers Fingers Fingers Fingers Fingers widely widely closely slightly slightly Finger and thumb positions spread spread grouped spread spread

Fingers closely grouped

Thumb Thumb fully fully abducted abducted

Thum fully abduc

Thumb Thumb partially partially abducted abducted

Thum partia abduc

Thumb fully Thumb fully adducted adducted

Thum fully adduc

a Even spread

The vast majority of swimmers keep the fingers grouped, slightly spread or widely spread.3 A slight gap between fingers (tip-to-tip) may be a 0.13 in (0.32 cm) distance. A wider gap tip-to-tip may go up to 0.25 in (0.64 cm). As far as the thumb is concerned, it may be fully abducted, partially abducted, or fully adducted. A fully abducted thumb makes an angle of roughly 68° with the index finger, while a partially abducted thumb is at an angle of about 30°. If the thumb is adducted it is near the index finger. So combining the three options for the finger spread and the other three for thumb position, we get nine possible arrangements.

d Optimum arrangement Summarizing research findings for a freestyle swimmer,3 for optimum thrust generation the fingers should be grouped and thumb adducted at entry, during “insweep” the thumb should be adducted and the fingers slightly spread, then as the hand starts to move out and upward during “upsweep” the thumb should be slightly abducted and the fingers grouped, and finally on exiting the water the fingers should CH1 SP7 G2_C once again be grouped and the thumb adducted.

When the hand starts to move out and upward (“upsweep” phase), the thumb should be slightly abducted and the fingers grouped.

Fingers widely spread

Fingers slightly spread

Fingers closely grouped

CH1 SP7 G2_D

Before exiting, the fingers should again be grouped and thumb adducted.

31

How much energy do I use when swimming?

One concern that competitive, recreational, and fitness-oriented swimmers have in common is the amount of energy expended in swimming. The reasons for this concern, though, are somewhat different depending on the swimmers’ motivation. For middle- and long-distance swimmers the goal is to swim efficiently, spending the smallest amount of energy possible at a given pace. Sprinters, on the other hand, aim for speed, and spend a large amount of energy as quickly as possible in order to achieve it—that is, they have a higher power output. Fitness-oriented swimmers are often more conscious of body composition, and the balance between energy input (the food calories they consume) and output (the intensity of physical activity). If you swim a few laps at different paces and using different swim strokes, it is clear that the “exertion” involved in each case—that is to say, the energy output required—is rather different. The amount of energy expended increases with swim speed, regardless of the chosen swim stroke, because the amount of drag to overcome increases with speed (see pages 18–19).1 Indeed there is a squared relationship between the two (drag = constant × velocity2) meaning that a small increase in the speed imposes a substantial change in the drag force. So, the escalation of energy expenditure with speed is explained by the increasing drag force.2 In terms of energy expenditure, freestyle and backstroke are the most economical swim strokes, whereas butterfly and breaststroke are the least economical. There are several biomechanical reasons underpinning this.3 To help understand the basic principle, think about a car in city traffic. Each time the car accelerates and brakes, energy is used to change its state of motion and overcome inertia. When maintaining a steady speed on the highway, however, there is no need to overcome inertia, so the movement is more economical. In

32

Hydrodynamics

stop-start traffic, the car uses much more fuel per mile or kilometer than on the open highway. The same is true in swimming. Those swim strokes that enable the swimmer to keep a more steady motion, with fewer fluctuations in speed and drag force, are arguably the most economical. Those that involve repeated acceleration and deceleration, conversely, impose additional mechanical work and therefore require higher energy expenditure.

d Stroke of work At a given pace, freestyle and backstroke are the most economical swim strokes. The third most economical stroke is butterfly, while the least economical is breaststroke. Note that the comparison among swim strokes is always at the same pace. A recreational swimmer may feel that it is harder work swimming a lap of freestyle than a lap of breaststroke, but she probably also swims faster at freestyle. So, the perceived rate of energy expenditure is confounded by the swim pace, which was not the same in the two trials.1 Energy expenditure for swim strokes 110 Energy expenditure (ml O2 absorbed/kg body mass/min)

What is the energy expenditure of swimming?

100 90 80 70 60 50 40 30 20 10

1.0

1.4 1.2 Swimming speed (m/s)

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CH1_SP8_G2_BUTTERFLY 1_SP8_G2_BREASTSTROKECH1_SP8_G2_BACKSTROKE

Swimming speed

Drag force and energy expenditure

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Speed with drag force of 80 N: 1.39 m/s

Speed with drag force of 80 N: 1.75 m/s

Speed with drag force of 40 N: 1.21 m/s

Speed with drag force of 40 N: 1.51 m/s

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Swimming speed (m/s)

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Backstroke

Freestyle

Speed using 70 ml: 1.225 m/s Speed using 50 ml: 1.025 m/s

Speed using 70 ml: 1.3404 m/s Speed using 50 ml: 1.125 m/s

Speed using 70 ml: 1.420 m/s Speed using 50 ml: 1.225 m/s

Speed using 70 ml: 1.575 m/s Speed using 50 ml: 1.344 m/s

o Drag race The amount of drag force acting on the swimmer is lower for freestyle than for the other swim strokes.1,4 This is because there is less change in the swimmer’s mechanical impulse along the stroke cycle, which leads to smaller variations in swimming speed for freestyle. Speed fluctuation is higher for breaststroke and butterfly than for the other strokes, as indicated by the greater thickness of the shaded area in the upper graphs.3

33

How efficient is propulsion at the competitive level?

How can I swim faster in competitions?

For optimum performance, distance swimmers aim to achieve an economic and efficient technique. Coaches teaching novice swimmers also put a great deal of emphasis on efficiency—a good swimming technique means more of the energy available to a swimmer is expended in overcoming the drag force and propelling the body forward, which in turn means a faster swimming speed than for swimmers with poor techniques. There are various ways of expressing efficiency, but one of the most helpful to consider is the propelling efficiency, because it is strongly related to competitive level—elite swimmers show a far greater propelling efficiency than those competing at a lower level.1–4 Mechanically, propelling efficiency is the amount of energy used to overcome the drag force and displace the body in the water, as a proportion or percentage of the total energy required to overcome drag and to move the limbs, plus the energy transferred to the water, which accelerates the water away from the body. (Note that some researchers assume that the energy needed to move the limbs can be neglected.)

So, when the energy used to overcome drag and propel the body forward comprises a smaller proportion of the total energy, this means a lower efficiency. For example, if a swimmer has a high stroke cadence (rapid limb movement) but is not propelling the body with speed, he is probably transferring a large amount of energy to the water, and using a relatively small proportion of the available energy to overcome drag and displace the body forward—so he’s swimming with low efficiency. Indeed, propelling efficiency can be assessed as the ratio between the speed of the body and the speed of the limbs. A swimmer that is able to displace the body quickly using a slower limb speed is more efficient than who one displacing at the same speed but with a higher limb speed.

d Waste not Propelling efficiency can be expressed as a percentage—it is the percentage of the total energy available to a swimmer that is used in overcoming the drag force and accelerating the body forward in the water. The bigger this percentage, the less energy is wasted, and the higher the swimmer’s efficiency. Energy used to move limbs

Propelling efficiency

Energy from respiration in muscles

Energy doing useful work

Energy used to move water

Energy wasted as heat

Propelling efficiency

34

Hydrodynamics

=Energy used to overcome drag

Energy used to overcome drag

Wasted energy transferred to water

Energy used to overcome drag

+ Water energy transferred to water + Energy used to move limbs

x 100%

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a Boosting efficiency

In training sessions, swimmers often use aids such as paddles or fins. On average, performing sets of full-stroke freestyle with paddles or with fins enhances efficiency by about 10%, from 60% to 70%.3,5 Wearing a monofin and performing fully immersed dolphin kicks with no arm movements achieves an efficiency of almost 80%.6 Conversely, a flutter-kick with no arm stroke (that is, not moving the arms) has been reported as being only 35% efficient.1 Aids such as fins and paddles increase the propelling surface, so a larger mass of water can be accelerated at the same limb speed. This means a greater displacement for the same energy output, and ultimately leads to a higher efficiency.

Full freestyle stroke, no aids

Full freestyle stroke, with fins

Full freestyle stroke, with hand paddles

Flutter-kick, with no arm stroke

Monofin dolphin kicks, with no arm stroke

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Olympic swimmer

Efficiency with training aids

o Elite efficiency How does efficiency compare in a young swimmer, an adult competitive swimmer, and an Olympian, in freestyle, for instance? As you might expect, efficiency increases with competitive level. Young swimmers have the lowest efficiency, followed by adult competitive swimmers, and the Olympians show the highest value. Young swimmers that compete on a regular basis have an efficiency of about 30% for freestyle,2 while an adult swimmer that races at national championships displays an efficiency of roughly 60%,3 and for an Olympic competitor the figure is around 70% efficiency.4

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What is the effect of wave resistance when swimming at the surface?

How can I reduce wave-making drag?

The total drag force on a swimmer is the sum of three components: the skin friction drag, the pressure drag, and the wave-making drag (see pages 18–19). However, the relative contribution of each component to the total drag is not equal— for a swimmer at the surface, wave resistance accounts for up to 50% of the total, while pressure drag and the skin friction drag account for 42.5% and 7.5% respectively.1,2 Obviously, swimmers want to reduce the total drag acting on them as much as possible. So, many swimmers focus on strategies to decrease the primary source of resistance, which is the wave-making drag. Counterintuitively, perhaps, the total drag force is much higher at the surface than when a swimmer is fully immersed. When moving at the air–water interface, the body piles up and compresses the fluid, making waves. The wave-making drag increases with speed, and because it is a cubed relationship (see pages 18–19), marginal increases in speed impose very significant increases in wave-making drag.1 For this reason, to cut down the wave-making drag when racing, it makes sense for a swimmer to stay immersed for as long as possible after the start and after each turn, performing dolphin kicks.

How can this dolphin-kick motion be made as efficient as possible? To quantify the efficiency of the wave motion we can calculate the Strouhal number. This is a dimensionless number (it has no units of measurement) describing the oscillating flow mechanisms at play—or the ratio between unsteady and steady motion (see pages 16–17). Basically, it is the ratio between the speed of the kicking toes and the speed of the body. The toe speed depends on the kicking frequency and amplitude. The lower the Strouhal number the better, because this means less propulsion is needed to reach a given body speed. It has been reported that national and international level swimmers have average Strouhal numbers of 0.95 and 0.79, respectively.3 Dolphins and whales show a Strouhal number between 0.2 and 0.4.4 Interestingly there is anecdotal evidence of some swimmers reaching Strouhal numbers as low as 0.59 and 0.45.5

NEED TO KNOW Strouhal number =

kicking frequency × kicking amplitude body speed

Dolphin-kick motion

a Kicking efficiency

36

Hydrodynamics

For a certain body speed, when the wavelength is shorter, the frequency increases. Wavelength Amplitude

The dolphin kick produces a pattern of vortices in the swimmer’s wake (see pages 16–17). Increasing the kicking frequency (so each kick is performed in less time) and/or decreasing the kicking amplitude (so there is less vertical displacement), for the same body speed, results in a more efficient dolphin kick. When it comes to performance, the kick has a much smaller impact compared to arm motions, but it pays to make it as efficient as possible.

Body speed

a Full immersion

Surface drag

When a swimmer is fully immersed, the wave-making drag decreases. For example, the average speed of the men’s 100 m butterfly gold medalist at the Rio 2016 Olympics, Joseph Schooling (Singapore), was 1.99 m/s (4.45 mph). This graphic shows that when swimming at this speed at the surface the wave-making drag is almost 110 N, but when the swimmer is fully immersed this drops to about 55 N, an improvement of around 50%. This is why, after the start and the turn, swimmers stay fully immersed for as long as possible, performing dolphin kicks. However, they can’t stay underwater forever—under swimming rules, athletes must break the surface before the 15 m mark.

110N

At swimming speed of 2 m/s

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The magnitude of the wave-making drag depends on the level of immersion—that is, how deep the swimmer is. The maximum wave drag occurs between the water surface and a depth of 0.55 yd (0.5 m)—as a swimmer goes deeper than this, the wave drag decreases. But if she sinks too deep, she will be spending too much time in vertical displacement and take longer to reach the opposite wall. So a compromise is needed. Evidence suggests that the effect of wave-making drag is negligible at depths greater than 1.8 times the chest depth of the swimmer (the approximate distance between the sternum and the spinal column).6 Therefore, swimmers may use this value as a guideline for their optimum depth directly after the start and turn—so for a swimmer of chest depth 0.5 m, the ideal depth at which to glide is 0.5 × 1.8 ≈ 0.9 m.

Swimming at surface

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37

How do head and arm positions affect active and passive drag when gliding?

In the streamlined position, all body segments should be perfectly aligned, so that the resistance acting on the body is minimized (see pages 18–19). There has been much research to assess the drag on the body when gliding in a streamlined position. When the body is gliding or being towed with no action by the limbs, this is “passive drag,” whereas if the limbs are acting to propel the body this gives rise to “active drag.”1 To assess the effects of different head alignments when gliding, researchers have measured the passive drag on swimmers holding the head in different positions.2 A common mistake made by non-expert swimmers is to look forward when gliding. The head, instead of being aligned with the body, is raised, disrupting the alignment. Competitive swimmers, on the other hand, reduce drag by keeping the head either in a neutral position aligned with the torso, or dipped to look slightly backward.

Competitive swimmers use two different arm positions when gliding. In one, the arms are forward, with the biceps against the ears. The second technique keeps the arms back, with the elbows close against the torso. In breaststroke, swimmers adopt both arm positions. First, after the push-off, they glide keeping the arms forward. Then an underwater arm stroke is performed, and another gliding moment is held, this time with the arms back beside the torso. Research indicates that having the arms forward imposes less passive drag on the body than holding them back against the torso.3,4 Putting the research data together confirms that the optimum position for streamlined gliding, imposing least drag on the body, involves holding the arms straight forward with the upper arms against the sides of the head, and facing the head to look either directly down at the pool bottom or slightly backward.

Arm position 2.0

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Gliding speed (m/s)

In the moments after take-off from the blocks at the start of a race, or after a turn, a swimmer glides in a streamlined position, carried by the momentum gained from pushing off. Gliding occurs during some swim strokes too—for example, breaststroke swimmers glide after the legs’ kicking action. During the glide, if the limbs move, they will slow the swimmer down because the drag force increases. So, adopting a streamlined position for gliding is a key-factor in maximizing the forward thrust.

How should I hold my head and arms when gliding?

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a Up in arms

An experimental study reported that the average passive drag on gliding swimmers with their arms extended forward was 32 N, while if the arms were back alongside the body it was 46 N.3 Drag coefficient was also significantly higher in the armsbackward position.4

38

Hydrodynamics

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130 110 130 110 Passive drag (N) Passive drag (N)

o Keeping your head down The passive drag on swimmers being towed at different speeds, with the head in three different positions, was measured using an electromechanical device.2 As expected, the drag force increased with speed, regardless of the head position adopted. Compared with the raised head position, the drag was reduced by about 10% when the swimmer’s head was facing either directly down, in a neutral alignment with the torso, or facing slightly backward. So, when raised to look forward, the head seems to disrupt the laminar flow around the swimmer (see pages 16–17). Another study also pointed out that head position had a noticeable effect on the hydrodynamics, changing the wake around the swimmer.5

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50 50

CH1_SP11_G1_ CH1_SP11_G1_KEY CH1_SP11_G1_KEY

Head looking fo Head looking dir Head looking forward Head looking sli Head looking directly down (neutral) Head looking forward Head looking slightly backward Head looking directly down (neutral) Head looking Head looking directly Head looking Head looking slightly backward

forward

down (neutral)

slightly backward

39

This chapter on technique spans a variety of topics that are critical to performance. Optimizing swimming technique requires consideration of key physics concepts. Biomechanics is the application of mechanical principles to body movement. Hydrodynamics is the study of a body moving through water. The application of biomechanics and hydrodynamics makes it possible to determine the exact body movements that optimize technique for the fastest swimming. The chapter begins with information about how a fundamental concept of hydrodynamics (the drag equation) explains the relationship of key factors—swimming velocity, the active drag coefficient, the cross-sectional area of the body, and propulsive force. Succeeding spreads provide detail about the relationships of these key factors, and how the application of biomechanical principles can help to optimize performance. The chapter also considers the index of coordination, a concept that has the potential to make swimmers much faster than the current world records.

chapter two

technique Rod Havriluk

Do technique limitations affect a swimmer’s performance?

Can I still swim fast with a poor technique?

If you look at the fastest swimmers, you won’t always see the “prettiest” technique. Fast swimmers often have technique flaws—such as vertical and lateral head and body motion— that are obvious from above the surface. Unfortunately, these flaws are sometimes adopted by other swimmers just because they are characteristic of a fast swimmer. A thorough analysis shows that fast swimmers also have technique limitations that are not so obvious because they occur underwater. In addition, there are performance factors besides technique that are not noticeable.

oxygen uptake during increasingly intense exercise (VO2 max). So a swimmer with apparently less than optimal technique may be winning races by offsetting such limitations with strength and conditioning. For example, a fast swimmer may have a drag coefficient that is only a little better than average, but may compensate with a peak hand force over 300 N and a maximum oxygen uptake over 70 ml/kg/min (milliliters of oxygen per kilogram of body mass per minute). There are other potential explanations for the race success of a fast swimmer with an obvious (above surface) technique limitation that are not related to superior strength or conditioning. One possibility is that the swimmer benefits from critical technique elements below the surface, which are not superficially apparent. Another is that opponents, while displaying better technique above the surface, may be hindered by more damaging technique flaws beneath the water. Swimming is complicated and a valid explanation of a swimmer’s success requires a thorough and objective evaluation of key performance factors. Nevertheless, studies have shown that, on average, the advantage faster swimmers have over slower swimmers is derived more from technique than from strength.1 This means that swimmers at any level can improve performance significantly by focusing on technique.

Three factors explain a great deal about swimming performance: technique, strength, and conditioning. The impact of each factor depends on age, ability level, and race distance. We can’t rely on naked-eye observation (or even video) to accurately evaluate technique. Technique is best measured by the active drag coefficient (Cd) (see pages 58–59), which includes data related to resistance, propulsion, and swimming velocity. Hand force (F) is used as a gauge of strength, while conditioning is measured by the athlete’s maximum rate of

a Not always perfect

Fast swimmers do not necessarily have optimal technique. The swimmer on the left (A) (representing Michael Phelps) has lifted his shoulders above the surface, which wastes energy. The biomechanical model on the right (B) keeps the shoulders below the surface as she recovers her arms, thus avoiding excessive vertical motion. Position A is more natural, but position B is more effective (see also page 51).

A

42

Technique

Contributions of strength and technique to performance

a Technique trumps strength

In a study to compare the relative contributions of strength (measured by average hand force, F) and technique (measured by the active drag coefficient, Cd ) to swimming performance, the magnitude of the difference between faster and slower swimmers in both F and Cd was calculated as an effect size.1 The mean effect size for Cd was almost double the effect size for F, indicating that faster and slower swimmers are differentiated more by technique (Cd ) than by strength (F).

Female swimmers Butterfly

Breaststroke

Freestyle

The drag equation

F=

⍴ACd v2 2

Backstroke 0

0.2

0.4

0.6 0.8 Magnitude of effect size

1.0

1.2

0.4

0.6 0.8 Magnitude of effect size

1.0

1.2

where: F = hand force (strength)

⍴ = density of water A = cross-sectional area of swimmer Cd = active drag coefficient (technique) v = velocity of swimmer relative to the water Measuring strength and technique For making comparisons, strength, technique, and performance are quantified—strength as average hand force (F ), technique as active drag coefficient (Cd), and performance as swimming velocity (v ). Higher force values mean more propulsion, while a lower Cd indicates a more effective technique. Conveniently, the drag equation includes F, Cd, and v, and makes it possible to gauge the relative contribution of component factors. The equation shows that F (strength) is proportional to the square of velocity (F ∝ v 2) and that Cd (technique) is proportional to the reciprocal of the square of velocity (C d  ∝ 1/v 2).

Male swimmers Butterfly

Breaststroke

Freestyle

Backstroke 0

0.2

Mean effect size for drag coefficient, Cd Mean effect size for hand force, F

B

43

How is hand force related to swimming velocity?

If I pull and push harder, will I swim faster?

In swimming, the resultant propulsive force generated by the hand during the stroke cycle is called the hand force, and it is directly related to swimming velocity—the greater the hand force, the faster the swimming velocity. The relationship is reflected in the drag equation (see page 43), which shows that force (F) is proportional to the square of velocity (v). We can write this as:

F ∝ v2

or

Increasing hand force becomes critical at higher swimming velocities, when a disproportionately large increase in hand force is necessary to increase swimming velocity further. For example, in the lower velocity range, a hand force increase of just 2.2 lb (10 N) could result in a 0.11 yd/s (0.1 m/s) increase in velocity—but at higher velocities, a 4.5 lb (20 N) force increase would be needed to yield the same step up in velocity. So it’s essential to increase hand force throughout the stroke cycle. To swim as fast as possible, a swimmer must pull and push as hard as possible—there are training techniques that can help maximize the propulsive force and speed.1

v ∝ √F

This theoretical relationship between hand force and swimming velocity has been supported with extensive research. Sensors are worn on the swimmer’s hand to measure the pressure differential between the palm and the back of the hand. The swimmer sprints 22 yd (20 m) toward the wall, where the camera is positioned, and data is captured over the last 11 yd (10 m). Hand force is calculated from the pressure data and the surface area of the swimmer’s hand.

a Use the force

44

Technique

CH2_SP2_G1_FIG Line weights

Hand force and velocity 2.5

Swimming velocity, v (m/s)

Hand force is directly related to swimming velocity. In an investigation, two female and two male swimmers successively increased their hand force over a series of ten trials.2 Hand force and swimming velocity were measured, using sensors as shown, and underwater cameras. The graphs show how each swimmer’s velocity increased with increases in hand force. Notice that the same curvilinear relationship exists for males and females of all ability levels. The graph lines are curved as shown because v is proportional to √F. (If v were proportional to F, the relationship would give a straight line.) This means that increases in F result in smaller and smaller increases in v. For example, here, if F increases from 40 to 60 N, v increases by about 0.2 m/s. If F increases from 140 to 160 N, v increases by only about 0.1 m/s. From this, it is clear that as swimmers progress major increases in strength are necessary to continue to increase swimming velocity.

Of course, the relationship between force and velocity applies to both the propulsive force (hand force) and to the resistive force acting against the body. So as a swimmer gets faster, the resistance goes up, by larger and larger increments— because the force is proportional to the square of the velocity. To maintain a constant swimming velocity, the propulsive force must equal the resistance at any given velocity.

2.0 1.5 1.0

CH2_SP2_G1_KEY CH2_SP2_G1_KEY

0.5

CH2_SP2_G1_KEY CH2_SP2_G1_KEY 0

0

20

40

60

80

100

120

Hand force, F (N) Faster female Faster male Faster female Slower female Slower female Slower male Faster Faster male male Slower Slower male male

140

160

180

200

Faster Faster female female Slower Slower female female Faster male Faster female Faster male Slower male Slower male Slower female

Sensors measure hand force

d Different strokes

Hand force analysis captures underwater video synchronized with hand force data, and provides useful information about a swimmer’s technique. The shape of the force curve identifies effective and ineffective elements of the stroke. Here, the data show how rapidly flexing the elbow too late in the stroke cycle produces a force loss on every stroke of more than 60 N. 3,4 Note: The forces shown are “normal” or perpendicular to the hand. Research shows that there is a trivial difference between normal and propulsive force.3

200

Underwater video analysis

Left hand

Hand force (N)

160 120 80 40 0 200

Right hand

Hand force (N)

160 120 80 40 0

Time

Typical curves Here, the rapid, steady force increase shows the swimmer is using strength effectively throughout the whole stroke cycle.

Here, there is a major force loss in the middle of the stroke, due to a sudden change in hand path, pitch, or speed.

45

Can hip rotation increase propulsion in freestyle?

Will I swim faster if I roll my hips side to side?

Many sports movements take advantage of the concept of “summation of forces” in which adjacent body segments sequentially rotate in the same direction to produce maximum force. For example, in kicking—in the water or on land—force is maximized by sequentially rotating the upper leg, lower leg, and foot about the hip in the same direction. There have been attempts to apply the summation of forces idea to the arm and torso motion in freestyle swimming—for example, suggesting that propulsion is generated by rotation of the torso, in the same way that hip rotation helps a baseball batter hit the ball with greater force.1 In batting, however, the hips, torso, shoulders, upper arms, lower arms, hands, and bat sequentially rotate in the same direction to generate maximum force. Conversely, in freestyle swimming, although the timing of the push phase (where the arm moves from beneath the shoulder back toward the feet) is usually simultaneous with upward hip rotation, the arm and hips are moving in different directions. The arm motion is perpendicular to the hip rotation—the hips rotate about the polar axis (through the center of the body from head to feet), while the arm pushes backward in a horizontal direction.

Because of this, the hand force cannot be increased by the force of torso rotation—rotating the hips harder or faster will not increase hand force. There is a natural tendency in freestyle to simultaneously move the hand and hips at the same time and in the same direction (upward, toward the water surface), which may contribute to the misconception that hip rotation helps generate propulsion, but this upward hand motion would actually generate less propulsion. A key factor in improving the freestyle push phase is to focus on simultaneously moving the hand and torso in different directions—the hand moves backward while the torso rotates upward. In fact, the term “hip rotation” can be misleading from the standpoint of either propulsion or resistance. It is more appropriate to refer to “torso rotation,” which helps emphasize that the shoulders and hips rotate together. Torso rotation enables the swimmer to position the arm in the water with better leverage to generate more propulsion and makes it easier to recover the arm that is out of the water closer to the body to reduce resistance and shoulder stress.

Batting torso rotation

Force production

46

Technique

g In the swing In batting, the torso rotates in the same direction (horizontal) as the arm and bat. Body segments rotate in succession to sum forces: torso, upper arm, lower arm, hands. With each successive body segment, force increases until the ball is hit. The red line indicates the side of the torso as the batter rotates.

Freestyle torso rotation

Hand force analysis

The push phase of freestyle is from when the arm passes under the shoulder until it stops moving backward.

Hand force (N)

Swimmer 1

200 160 120 80 40 0

Right hand

Time

The push phase is effectively synchronized with upward rotation of the torso on the same side as the pushing arm.

Hand force (N)

Swimmer 2 320 280 240 200 160 120 80 40 0

Right hand

Time

To maximize force on the push phase, the swimmer must push the hand backward while the torso rotates upward on that side.

o Pushing back Hand force analysis shows that force generation is limited when the elbow moves upward to the surface with the upward motion of the torso. In the upper panel, swimmer 1 cannot increase his hand force on the push phase because his elbow moves the hand upward with the torso rotation, rather than backward. In the lower panel, swimmer 2 achieves more effective force generation during the push phase by pushing his hand back while his torso rotates up. As he completes his push phase, his elbow is still submerged and his force increases to a peak. g Turning up Contrary to the case for batting in baseball, for a freestyle swimmer the torso rotates perpendicular to the hand and arm motion, rather than in the same direction —the torso rotates about the polar axis (running from head to feet), while the hand moves horizontally backward. This torso rotation cannot add force to the horizontal arm motion.

The elbow remains submerged as the push phase is completed, and force generation peaks.

47

equipment: synchronized underwater video and force analysis Most of the time, a coach analyzes a swimmer’s technique with naked-eye observation from the pool deck. This procedure generally limits the arm analysis to movements above the surface as very little of the underwater movement can be clearly seen. While the above-surface movements are important, the propulsion is generated by the arm movements under the water. Even a video of the below-surface movements still only provides a qualitative analysis —a quantitative analysis is necessary to determine the effectiveness of the motion captured by video. Analysis using above-surface video began in the 1960s, but was fairly rare. Underwater video became popular in the 1970s, but by the end of the last century, even though video was more widely accessible, it was not extensively used— indeed, most swimmers are still not analyzed using video on a regular basis. This may be because coaches haven’t found much benefit from the purely qualitative data it provides. More sophisticated systems of analysis were developed at the beginning of the 21st century to integrate hand force measurements with underwater video to instantly provide quantitative data to coaches and swimmers. Immediately after a swimmer completes a trial, the system calculates swimming velocity, stroke rate, stroke length, and the active drag coefficient, as well as numerous force and time variables. Hand force data is vital because it is directly related to swimming velocity. Studies on all four competitive strokes show not only that faster swimmers generate greater hand force, but also that when individuals increase their hand force, they swim faster. The arm is responsible for most of the propulsive force and the hand contributes most of the arm propulsion. 48

Technique

Straps to hold wires close to swimmer's body Sensor Wire to poolside computer

Camera A Wire to computer This sensor is held in between the third and fourth fingers. The sensor measures the pressure differential between the palm and the back of the hand. A is on the palm side in hand and is the positive port. Directly opposite A, on top of the sensor, is the negative port.

A quantitative analysis is essential for a competitive swimmer because it provides the most complete and accurate feedback. An analysis using only video shows the swimmer’s movements—quantitative force data is necessary to determine the effectiveness of each movement. Evaluation of specific body parts helps swimmers understand the technique adjustments necessary to swim faster. The video and force analysis make it clear to the swimmer how precise adjustments over small fractions of a second can produce dramatic increases in force that translate to substantial performance improvements.

Poolside analysis Camera and sensors are hard-wired to a poolside computer, providing synchronized data for instant analysis.

Camera captures video of swimmer directly approaching end wall.

g Instant feedback Synchronized underwater swimming analysis systems instantly and simultaneously capture underwater video and force data. A camera focused down the swim lane provides video images, while sensors attached to the swimmer provide the hand force data (see pages 44–45). Immediately after a trial, the data can be displayed to the coach and swimmer on a poolside laptop.

Sensor

Frame-by-frame data

d a Results are in

A frame-by-frame analysis of the synchronized video and hand force data clearly shows the motions that generate force, as well as those that are unproductive or that lose force. The coach can use this information to reinforce effective technique elements and help a swimmer change those elements that limit performance.

CH1_SP3A_EQUIP_G5

File Clients Data Diagnostics Channels Gain Limb Units Rate Sensors Help Force (N) 40 32 24 17 8 0

Left Hand/Channel 1

Fly Pull Fly Recovery

Trial 00.01.54

Rep 2

0.02

Trial 00.01.54

Rep 1

0.76

A hand force analysis can also display the force curves for the opposite hand in outline, allowing coaches and swimmers to evaluate the pattern of arm coordination (see pages 52–53)

CH1_SP3A_EQUIP_G4 40 32 14 17 8 0

Right Hand/Channel 2

File Clients Data Diagnostics Channels Gain Limb Units Rate Sensors Help Force (N) 200 120 90 60 30 0

200 120 90 60 30 0

Left Hand/Channel 1

Right Hand/Channel 2

Fly Pull Fly Recovery

Trial 00.01.76

Trial 00.01.76

Rep 2

Rep 2

0.26

0.24

Here, for example, a force analysis for an Olympic butterfly swimmer is shown. Conventional wisdom might recommend that novice swimmers replicate his stroke movements, since he has clearly had some success. However, the hand force data shows that as he begins his butterfly pull with lateral motion, he generates only a trivial amount of force. So this aspect of his stroke form could clearly be improved. (The red bars show the duration of minimal force—the ends of the bars are synchronized with the video image.)

49

Can body undulation increase propulsion in breaststroke and butterfly?

Will moving up and down in the water make my breaststroke and butterfly faster?

Many swimmers have noticeable vertical motion in breaststroke and butterfly. Upward movement of the head and shoulders is clearly evident, particularly on breathing strokes. Excess upward motion to breathe typically results in excess downward motion after the breath, with the legs moving in the opposite direction to the torso. This produces rotation about the hips, and gives the appearance of an undulation or wave-like motion from the head to the feet.

When a swimmer emphasizes undulation, this inevitably leads to excess vertical elevation of the body, with two negative consequences. First, the angle of the torso presents a greater resistive area in the direction of movement. Second, upward shoulder movement slides the arms upward so that they cannot generate as much propulsion. The natural tendency to go up and down on every stroke cycle causes more resistance and less propulsion.

Swimmers typically acknowledge that they try to go up and down when they swim butterfly or breaststroke, or at least that they feel like they go up and down. A common misconception is that an emphasis on undulation is necessary for an effective butterfly or breaststroke, and indeed there are many commonly used drills that promote vertical motion and undulation. This is unfortunate as an optimal butterfly or breaststroke actually involves minimal vertical motion or undulation.

There are three primary factors that can help a swimmer minimize vertical motion, and so swim faster. First, keep in mind that the race is horizontal and not vertical to stay focused on moving forward. Second, breathe by extending at the neck instead of lifting the head. And third, do not make a conscious effort to vertically move the shoulders or hips. Minimum vertical motion and undulation keeps the body relatively level and provides a stable base of support for maximum arm propulsion.

CH2_SP4_G1_A

CH2_SP4_G1_C

Head and shoulder positions

CH2_SP4_G1_B

Breaststrokers often elevate the head more than necessary when breathing, as here. Above-surface recovery, where the hands move forward above the water, also contributes to excess upward motion.

A

50

Technique

The breaststroker here has her body almost vertical when breathing. In addition, her neck is not extended, so she lifts her head far above the surface.

CH2_SP4_G1_D

B

Excess vertical motion under water

150° 220°

o Under the surface

When a swimmer has excess vertical motion of the head and shoulders above the surface, it’s usually followed by excess vertical motion below the surface. In these images, compare the head positions of the butterflyer (left) and the model of optimal technique (right). Not only does the excess vertical motion increase resistance and decrease propulsion, but the angle at the shoulders is extremely stressful. This shoulder-stressing position often causes shoulder impingement, which is extremely common in competitive swimmers.

Position after arm entry

d Moving on up

Most swimmers have excess vertical motion in butterfly and breaststroke. Even some of the world’s fastest swimmers lift their head and shoulders considerably above the surface when breathing in breaststroke and butterfly. The model images below each example (A and B for breaststroke/C and D for butterfly) show how, instead of lifting the head and shoulders to breathe, a swimmer can extend at the neck so the body stays relatively level and resistance is minimized.

In addition to excess verticalNEW_CH2_SP4_G1_1 motion of the head and shoulders, this butterflyer is not extending his neck to breathe, which means he must lift the head higher above the surface.

CH2_SP4_G1_2

o Keeping your head

The left and center images here show butterfly swimmers in typical positions after arm entry. Both swimmers have submerged their heads, one with the arms below the shoulders (left) and one with the arms above the shoulders (center). The model on the right has an effective arm entry, where the head is maintained at the surface.

CH2_SP4_G1_3 Here also the butterflyer has minimal neck extension so he has to lift his whole upper body above the surface to breathe. The consequent angle of the torso increases resistance.

CH2_SP4_G1_4

C

D

51

What is the optimal index of coordination?

How do I time my arm strokes to swim faster?

In 2000, three scientists developed an index of coordination (IdC) to quantify the relative positions of the arms throughout the stroke cycle in freestyle.1 They explained that when one hand begins to pull at the same time as the opposite hand completes the push, the arms are in opposition and the IdC is zero. If the pulling (entry) arm remains motionless while the opposite arm begins the recovery, the IdC is negative (also called “catch-up” stroke). If the pulling arm begins to generate force before the push is complete, this is called superposition, and involves a positive IdC. Superposition maintains a more continuous source of propulsion, and therefore more constant body velocity (see pages 54–55).

Some arm coordination differences in freestyle can be detected with the naked eye from the poolside. For example, some swimmers show noticeable phases of body acceleration and deceleration. A negative IdC is usually responsible for these fluctuations in body velocity.

Index of coordination (IdC) % –35

Research has shown not only that a positive IdC differentiates expert and non-expert swimmers,2 but that for expert swimmers the IdC increases with increasing speed, while non-expert swimmers do not significantly change their arm coordination as they swim faster. That is, non-expert swimmers tend to maintain a negative IdC, even at higher swimming velocities.

Arm coordination for fastest freestyle –30

–25

Negative index of coordination: If the pull (entry) arm remains motionless while the opposite arm begins the recovery, the IdC is negative (also called catch-up stroke).

–20

–15

–10

–5

Zero index of coordination: If the pull arm begins to generate force as the opposite arm completes the push, the IdC is zero (also called opposition).

Hand force per stroke (N)

270

225 180 135 90 45 0

0.2 second gap between left and right arm strokes

52

Technique

No gap between left and right arm strokes

a Technical challenge

This table and the graphic below show that superposition arm coordination is the most effective way to make substantial increases in maximum swimming velocity. However, achieving an IdC greater than 30% requires superior technique with exceptional precision and control.

Arm coordination

Position gap or overlap

Index of coordination (IdC)

Average force per hand (N)

Swimming velocity (m/s)

Catch up

0.2 sec gap

–20%

51

1.8

Opposition

No gap or overlap

0

64

2.0

Superposition

0.2 sec overlap

+33%

85

2.3

Many swimmers have a negative IdC, for a variety of reasons. Some intentionally maintain the arm in a motionless position after the entry, as in “catch-up” stroke. Other swimmers unintentionally delay the start of the pull due to an ineffective arm entry, wasted (lateral) hand motion, or fatigue. Swimmers usually complete the arm entry by straightening the arm parallel to the surface. In the resulting position, it is only natural to “rest” the arm and delay beginning the pull. In addition to increasing the time for each stroke cycle, “catch-up” coordination puts the arm in a position of poor leverage, making it difficult to begin the pull. As a result, the parallel arm entry position restricts a swimmer’s ability to swim with a positive IdC.

0

5

10

15

d Closing the gap The graphic shows how dramatically different the average hand force and swimming velocities are for three different arm coordinations (assuming that the underwater arm motion is the same for all three coordinations). The velocity values were calculated from the drag equation, using drag coefficient and body cross-section values for an elite swimmer (see pages 42–43). The force applied at each point throughout the stroke cycle is the same for each index of coordination—the average hand force varies, however, because the time for one stroke cycle is different for each IdC. Notice that for this same application of force, the swimming velocity is greatest when the arm coordination is superposition. The graphic shows a 0.2 s overlap in the force curves, for an IdC of 33%.3,4 While expert sprinters usually have a positive IdC of less than 5%, an IdC over 30% is possible and necessary for the fastest swimming.

20

25

30

35

Positive index of coordination: If the pull arm begins to generate force before the push is complete, the IdC is positive (also called superposition).

Left hand Right hand 0.2 second overlap between left and right arm strokes

53

Why is it important to maintain a constant body velocity? A relatively continuous source of propulsion produces a more constant body velocity for a more efficient use of energy. The result is the fastest swimming over a given distance. While a constant velocity strategy is most efficient, it is also very demanding and very fatiguing. Consequently, swimmers naturally find ways to “rest” by gliding. Body velocity slows rapidly when there is no propulsion, such as during the glide after a start or a turn. Most swimmers slow to swimming velocity within one second. It is natural to keep gliding to avoid the effort of generating propulsion. However, a swimmer who glides for more than one second will immediately lose ground to competitors. It is essential to begin a propulsive action as soon as the body slows to swimming velocity. There are often dramatic fluctuations in body velocity within each stroke cycle that indicate a swimmer would prefer to “rest” rather than maintain a more continuous source of propulsion. For example, just as after a start or turn, swimmers often maintain a streamlined position after each stroke of breaststroke and lose more than 10% of their velocity in

Is it ever good to glide? one-tenth of a second. “Resting” after the arm entry during butterfly is also common. Swimmers often dive underwater and glide to avoid immediately generating propulsion. In freestyle, it is extremely common for swimmers to complete the arm entry and then glide. It is so common that the strategy even has a name—“catch-up stroke.” Considerable research has shown the adverse impact of this “negative index of coordination (see pages 52–53).”1 In all four strokes—breaststroke, butterfly, freestyle and backstroke—it is important to maintain a continuous source of propulsion. In breaststroke and butterfly, immediately beginning the pull after completing the arm recovery is critical. In freestyle and backstroke, it is important to coordinate the arm motion so that one arm begins the pull as the other arm completes the push. The only time that gliding is recommended is when the body is moving faster than swimming velocity—that is, for a fraction of a second immediately after a start, a turn, or possibly after the kick phase in breaststroke.

CH2_SP5_G1 A Fluctuations in body velocity 4.0 4.0

The first graph shows how quickly the body velocity drops after a start, with no propulsive motions of any stroke.2 The swimmer simply dives in and, after the entering the water, glides for the time shown on the graph. In less than 1 s, the body velocity has dropped below 2 m/s. The second graph shows how body velocity changes during one breaststroke cycle.3 Here, gliding for only 0.2 s results in a drop in velocity of about 20%. The third graph shows the data for one butterfly stroke cycle.4 The velocity slows after the arm entry, as the swimmer delays exerting much propulsive effort at the beginning of the pull.

Body (m/s) Bodyvelocity velocity (m/s)

a Losing speed fast

Start(glide (dive and no propulsion) Start only, no glide, propulsion)

3.5 3.5 3.0 3.0

2.5 2.5 2.0 2.0 1.5 1.5 1.0 1.0 0.5 0.5 0

0.0 0

54

Technique

0.5 0.5 Time (s)

1.0 1.0

1.5 1.5

2.0 2.0 Time (s)

2.5 2.5

3.0 3.0

3.5

4.0 4.0

CH2_SP5_G3 FIG C Index of coordination Zero index of coordination

Positive index of coordination

CH2_SP5_G3 CHART C

270 270 225 225 180 180 135 135 90 90 45 45 00

If the pull arm begins to generate force as the opposite arm completes the push, the IdC is zero (also called opposition). Left hand

0.4 0.8 0.8 1.2 1.6 2.0 2.4 3.2 3.6 3.6 4.0 2.4 2.8 2.8 3.2 0 0.4 Time (s)

Right hand

CH2_SP5_G2

Propulsion comparison

Left hand

Right hand

Negative index of coordination: gaps in propulsion 135 225 90 180 45 135 0 90

Left hand

Right hand

Negative index of coordination: gaps in propulsion

Right hand

Right hand

CH2_SP5_G1 B

g Keeping it constant

The top graph shows the swimmer has overlaps in arm propulsion for a more continuous source of propulsion and a more constant body velocity. (The force curves in solid blue are for the left hand and the force curves in outline are for the right hand.) A positive IdC avoids gliding between strokes. In the lower graph, the swimmer has gaps in propulsion which results in large fluctuations in swimming velocity. With this negative IdC a swimmer has some “rest” between strokes. However, the body velocity slows considerably and the swimmer loses ground to competitors with a positive IdC. CH2_SP5_G1 C

Breaststroke Breaststroke

3.2 3.2

Butterfly Butterfly

2.8 2.8

Glide

Kick recovery

0.0 0.1 0.2 0.2 0.3 0.3 0.4 0.4 0.5 0.5 0.6 0.6 0.7 0.8 0.9 0.9 1.0 1.0 1.1 1.1 1.2 1.2 1.3 1.3 0.7 0.8 0 0.1

Time (s)

Time (s)

velocity(m/s) (m/s) BodyBody velocity

Hand force Hand (N) force (N) Hand force Hand (N) force (N)

Hand force (N)

45 Negative index of coordination: gaps in propulsion 225 0 180

Body velocity (m/s) Body velocity (m/s)

Hand force (N)

Positive index of coordination: continuous propulsion Positive index of coordination: continuous propulsion

1.8 1.8 1.6 1.6 1.4 1.4 1.2 1.2 1.0 1.0 0.8 0.8 0.6 0.6 0.4 0.4 0.2 0.2 0

Left hand

The model shows different arm coordinations: zero (left), and positive (right). Hand force curves for each coordination index are also shown. Arm coordination is categorized by the index of coordination or IdC. A negative IdC produces gaps in propulsion while the swimmer glides between strokes. With a positive IdC, the hand force curves overlap for a more continuous source of propulsion, and therefore more constant body velocity.

225 225 180 180 Positive index of coordination: continuous propulsion 135 135 225 90 90 180 45 45 135 0.0900

2.0 2.0

0 0.4 0.8 1.2 1.6 2.0 2.4 2.4 2.8 3.2 1.6 2.0 3.2 3.6 3.6 4.0 4.0 Time (s)

o Smooth and speedy

CH2_SP5_G2

Left hand

If the pull arm begins to generate force before the push is complete, the IdC is positive (also called superposition).

Time (s)

Time (s)

225 180 135 90 4545 0.00

270 270 225 225 180 180 135 135 90 90 45 45 00

Hand force (N) Hand force (N)

Hand force (N) Hand force (N)

CH2_SP5_G3 CHART B

2.4 2.4 2.0 2.0 1.6 1.6 1.2 1.2 0.8 Beginning 0.8 of pull 0.4 0.4

0

Arm and leg recovery

0.0 0.1 0.2 0.2 0.3 0.3 0.4 0.4 0.5 0.5 0.6 0.6 0.7 0.8 0.9 0.9 1.0 1.0 1.1 1.1 1.2 1.2 1.3 1.3 0.7 0.8 0 0.1 Time (s) Time (s)

55

SCIENCE

IN ACTION

mechanical advantage

Mechanical advantage (also called leverage) is a key principle related to swimming fast. Swimmers benefit from leverage by changing the angle at both the shoulder and elbow as the arm moves backward. The concept of “leverage” applies because the attachments of the muscles to the bones (via the tendons) form levers within the human body. The mechanical advantage of most of these levers is poor due to the fact that the tendon of the muscle (providing the effort) is attached to the bone (lever) very close to the joint (fulcrum). A second factor is that for much of the range of motion, a muscle is pulling on a bone at a less than optimal angle. Changing the angle at the shoulder improves the leverage of the upper arm. Once the arm drops below the level of the shoulder, swimmers usually have a substantial increase in hand force.1 Changing the angle at the elbow improves the leverage of the lower arm—when the elbow begins to flex, hand force usually increases. Controlling the angle at the shoulder on the arm entry and at the elbow at the beginning of the pull is critical in all four strokes. Swimmers are at a rather extreme mechanical disadvantage when the arm is above the shoulder or when trying to generate propulsion with a straight arm. Once the arm passes under the shoulders in freestyle, it is critical to maintain backward motion of the hand (as shown in the photo opposite). Since the push phase of the arm is synchronized with the upward torso rotation, swimmers tend to naturally let the hand slide up with the torso. If a swimmer maintains backward motion of the hand, the elbow will be submerged far into the push phase and the hand will generate maximum force. An increase in strength increases the potential effort and, therefore, also the mechanical advantage.

a Maximum leverage

This shows how Olympic gold medalist Cesar Cielo bends his elbow to benefit from leverage. In addition, his elbow is submerged far into the push phase so that he can continue to push back with a great deal of force.

56

Technique

What is the drag coefficient?

What is the best way to evaluate my swimming technique?

Swimming technique is usually evaluated by naked-eye observation from the pool deck. Most of the time, coaches only have an above-surface (or limited below-surface) view of a swimmer’s technique. While this kind of qualitative evaluation during a workout is the standard and can effectively address a number of technique elements, a quantitative analysis is necessary for a complete and accurate evaluation. The drag coefficient (Cd) is generally considered the best measure of the effectiveness of technique. The passive drag coefficient measures drag on a static body pose (when gliding in a streamlined position, for example) and the active drag coefficient measures swimming motions. For either passive or active drag, the “shape” of the body determines the Cd. The lower the active Cd, the more effective the technique. Most swimmers who “look good” have a Cd that is below the average of 1.0 (for freestyle). There are many top Olympians with a Cd that is only a little better than average (such as 0.9). A Cd below 0.7 is rare.

A quantitative analysis is essential to determine technique improvements. Measurement of the active drag coefficient Cd before and after a training intervention is the only way to really determine if a swimmer’s technique has improved. The Cd simplifies technique evaluation to a single objective number, as opposed to a subjective assessment. According to the drag equation (see pages 42–43), the square of the swimming velocity v2 is inversely proportional to the drag coefficient Cd. So as the Cd decreases, swimming velocity increases significantly. At a swimming velocity of 1.86 yd/s (1.7 m/s), for example, a 0.1 improvement in the drag coefficient results in an improvement in swimming velocity of 0.11 yd/s (0.1 m/s). At a swimming velocity of about 2.19 yd/s (2.0 m/s), a 0.1 improvement in the drag coefficient produces an almost 0.22 yd/s (0.2 m/s) improvement in the swimming velocity. Because of the relationship between Cd and swimming velocity, even the most technically proficient swimmers can benefit by continuing to improve their technique.

Stroke speed comparison

Females Males

58

Technique

2.0 Swimming velocity (m/s)

These graphs show active drag coefficient (Cd) plotted against swimming velocity for 40 male and 40 female university swimmers. For each stroke, there is a statistically significant relationship between drag coefficient and swimming velocity – the lower the Cd (the better the technique), the higher the velocity.1

Butterfly

2.0 Swimming velocity (m/s)

a Drag down, speed up

1.5 1.0 0.5 0.0

0.0

0.5 1.0 1.5 Active drag coefficient, Cd

2.0

Backstroke

1.5 1.0 0.5 0.0

0.0

0.5 1.0 1.5 Active drag coefficient, Cd

2.0

Swimming velocity and active drag coefficient 2.4 2.3 2.2 2.1 2.0

Swimming velocity (m/s)

1.9 1.8 1.7 1.6

Average cross-sectional area 1000 cm2

1.5 1.4 1.3 1.2

Average force 140 N

1.1 1.0

0.0

0.1

0.2

0.3

0.4

0.5

0.8 0.6 0.7 Active drag coefficient, Cd

0.9

1.0

1 Cd

where v is the swimming velocity and Cd is the active drag coefficient.

Freestyle

2.0 Swimming velocity (m/s)

Swimming velocity (m/s)

2.0 1.5 1.0 0.5 0.0

0.0

0.5 1.0 1.5 Active drag coefficient, Cd

2.0

Breaststroke

1.5 1.0 0.5 0.0

0.0

0.5

1.0 1.5 2.0 2.5 Active drag coefficient, Cd

1.2

1.3

1.4

o Tiny improvements bring big rewards

NEED TO KNOW v2 α

1.1

3.0

There are proportionally bigger improvements in velocity with each incremental improvement (decrease) in active drag coefficient Cd. For example, a decrease in Cd from 1.0 to 0.9 increases velocity by 0.1 m/s (green triangle). In comparison, a Cd decrease from 0.7 to 0.6 increases velocity by almost 0.2 m/s (red triangle). So, even if a swimmer’s technique is “really good,” substantially faster swim speeds can be achieved by continuing to improve and reduce Cd. The data points for this graph were calculated from the drag equation (see pages 42–43), which shows the relationship of swimming velocity (v) and active drag coefficient (Cd), assuming an average force (F) of 140 N and a body cross sectional area (A) of 1000 cm2 (typical values for an elite male swimmer). The value for water density (ρ) is constant.

59

What impacts performance more, resistance or propulsion? Resistance and propulsion are equally important to performance. Whether a swimmer should first master streamlining (to decrease resistance, or drag) or pulling motions (to increase propulsion) depends on the individual. For example, if a swimmer’s legs are below the torso, causing an increase in the body cross-section, adjusting technique to lift the legs could cause a sudden improvement in performance by decreasing resistance. Other adjustments to decrease resistance may not have quite as dramatic an impact; however, they are often associated with the most basic skills. For example, the streamline position is the most basic in competitive swimming, yet many top swimmers have not mastered a perfect streamline. It is essential to master the streamline as it is fundamental to decreasing resistance and establishing an optimal base for generating propulsion. When swimmers begin a pull to generate propulsion (in any of the four competitive strokes), very often the arm is completely straight. Because a straight arm has poor leverage (that is, a low mechanical advantage), beginning the pull with a straight arm generates very little force. By flexing the elbow to begin the pull, the swimmer immediately gains better leverage, rapidly increasing propulsion, and could see a considerable time improvement.

A

Technique

Swimmers often lose force in the middle of the freestyle stroke, usually because of a sudden change in direction of the hand motion. Adjusting the hand path so that changes in direction are gradual can minimize or even eliminate force losses. Since hand force is directly related to swimming velocity, eliminating force losses can produce substantial improvements in performance. Force losses at the end of the stroke in freestyle are also common. Most swimmers let the hand exit the water prematurely as the elbow moves upward in synchronization with upward torso rotation. Gaining maximum propulsion requires moving the hand and torso differently—the hand must push backward as the torso rotates upward.

d Position of least resistance Faster swimmers tend to have a significantly improved drag coefficient compared to slower swimmers, both for active drag during swimming and for passive drag measured while gliding in the streamlined position.1 Since the drag coefficient is a measure of technique proficiency, this indicates— unsurprisingly, perhaps—that faster swimmers have better technique, both in terms of propulsion and streamlining.1 When gliding, many swimmers fail to streamline effectively. Drawing an oval around the shoulders, as shown here, shows the smallest cross-sectional area for a body that minimizes resistance or drag (B). When a swimmer’s body parts extend outside the oval (A), they increase the cross-sectional area the body presents in the direction of the gliding motion, and therefore increase passive drag. When swimming, as in breaststroke, it is more of a challenge to minimize the body’s cross-sectional area, and therefore drag. Note how the legs of the model (D) are positioned closer to the oval when compared to a typical swimmer (C).

Minimizing drag

Gliding (passive drag)

60

Should I master streamlining or stroke technique first?

B

200

2.5

160

2.0 Swimming velocity (m/s)

Resistive force (N)

Drag factor

120 80

CH2_SP7_G3

1.5 1.0 0.5

40

0.0

0.5

1.0 1.5 Swimming velocity (m/s)

2.0

2.5

0.0

20

40

60

80

100

120

140

CH2_SP7_G3 CH2_SP7_G3 Propulsive force (N)

160

180

200

Note: 1.0 m/s ≈ 1.09 yd/s

Elbow flexion

o Squaring up The drag equation shows that the size of the resistive force increases with the square of velocity (see page 43). So, if swimming velocity doubles (×2), the resistance increases by a factor of four (×22)—for example, in the graph (left), at a velocity of 1.0 m/s, the resistance is 40 N, while at 2.0 m/s, the resistance increases to 160 N. This means that at faster swimming speeds, small further increases in velocity cause large increases in resistance. For example, at 1.0 m/s, an increase in velocity of 0.2 m/s increases resistance by 20 N, while at 2.0 m/s, the same increase in velocity of 0.2 m/s increases resistance by 40 N. Propulsion must also increase to match and counter the resistance—because of the square relationship between velocity and force, greater increases in propulsive force are needed at higher speeds in order to achieve the same increments in velocity. For instance, at 1.0 m/s, an increase of 20 N in propulsive force produces a 0.2 m/s increase in velocity, while at 2.0 m/s, an increase of 40 N in propulsive force is needed to produce a 0.2 m/s improvement.

Flex

Flexed elbow for better leverage Straight arm has poor leverage

o Flex effect Optimizing technique is essential to maximize propulsive force. At the start of the stroke, the swimmer should immediately flex the elbow, to gain better leverage. A straight arm has a lower mechanical advantage, and cannot generate the propulsion that is so important at the beginning of the pull.

Swimming (active drag)

C

D

61

What hand pitch generates the most force?

How should I angle my hand to swim faster?

Hand pitch is the angle formed between the palm of the hand and the direction of the hand’s path through the water. Depending on the stroke and the point in the stroke cycle, a swimmer’s hand might be angled very differently. For example, the palm may be facing directly backward or completely toward the side. Hand pitch also varies between swimmers. In freestyle and backstroke, most competitive swimmers maintain their palm facing backward, relative to the body’s direction of motion, through much of the underwater arm motion. In butterfly, swimmers often angle their palms to the sides of the pool at the beginning of the pull and then angle their hands to face backward. In breaststroke, the palms typically first angle toward the sides and then toward the body midline.

d Making a pitch

The angle of hand pitch is the angle between the palm of the hand and the direction of its path through the water. Drag force is generated in a direction opposite to the hand path. Lift force is generated perpendicular to the path of the hand. The drag and lift vectors determine the size and direction of the resultant force.

Hand pitch

Research has been conducted to determine how the hand pitch affects propulsion. The flow of water around the hand has been likened to the flow of air around the wing of a plane, producing forces in a similar way. The hand motion produces a force in a direction opposite to the hand path (drag) and a force perpendicular to the hand path (lift). These component vector forces combine to determine both the magnitude and direction of a resultant force, which ultimately provides the swimmer’s propulsion. The wide variations between swimmers in hand pitch is surprising given that hand pitch is one of the most researched topics in swimming. In addition, there has been considerable consistency in the results among research groups carrying out experiments in which the hand pitch angle was changed and the resultant force was measured. Back in 1979, a study found that a 70° hand pitch angle produced the greatest resultant force, and since then multiple further research projects have confirmed these findings, suggesting an optimum hand pitch in the range 70° to 75°.1 62

Technique

Thumb Pinky finger Hand path angle Resultant force Drag Lift Hand path direction

Hand pitch angle

Force variation

a Pitch perfect

d Angling for success

The inward sculling motion in breaststroke is different from the pull-and-push phases of butterfly, backstroke, and freestyle. A hand pitch of 45° generates maximum force on a sculling motion. Here, the swimmer’s right hand is sliding sideways with very little pitch and generating only about 20 N. The left hand has a pitch of around 45° and is generating about 40 N.

120

Left hand

Range of greatest force for all six studies

100 90 Relative resultant hand force (%)

This graph shows the variation of force with the angle of hand pitch, as observed in six studies.1–6 The solid circles represent calculated force values from the study data. The colored lines are the best-fit trend lines to show the pattern more clearly. The red box shows the range of greatest force for all six studies. The overall results show that a hand pitch of 70° to 75° generates the greatest force.

80 70 60 50 40 30 20 10 0

0

5

10

15

20

25

30

35

40

45

50

55

60

65

70

75

80

85

Hand pitch angle (°)

Inward sculling motion

90 60

Hand force (N)

30 0 120

Right hand

20 (N)

40 (N)

90 60 30 0

63

90

Which hand path generates the most propulsion?

Should my hands follow a curved or a zigzag path?

The path of the hand in freestyle depends on whether it is graphed with respect to the water or the body—because the swimmer is moving forward relative to the water during the stroke cycle. The typical hand path that freestyle swimmers display is curved and S-shaped. However, the optimal hand path, giving the greatest propulsive force, is better described as a very gradual zigzag.1

adjusted to the swimmer’s frame of reference—the body.2 As the swimmer moves forward during a stroke cycle, the hand moves backward about twice as far with respect to the body as with respect to the water. The optimal hand path angle when considering the path with respect to the body, therefore, is about one-half the optimal angle when considering the path with respect to the water—that is, 12.5°.

To achieve the optimal hand path first requires using the optimal hand pitch—research shows that a hand pitch angle of 70° to 75° produces the greatest resultant force (see pages 62–63). It has also been found that the resultant force generated by the movement of the hand in the water is angled at 25° to the line of the hand path. So, to ensure that the resultant force acts in the forward horizontal direction of body motion, the swimmer must angle the hand path at 25° to that forward direction (with respect to the water)—that is, the hand must move from in front of the shoulder toward the body midline. When the hand path is angled in this way, the resulting hand pitch is approximately perpendicular to the horizontal direction of body motion—that is, with the palm facing backward.

An optimal hand path results from moving the hand at a gradual angle from in front of the shoulder to beneath the head, and then changing direction to angle the hand from under the head to beneath the thigh. If the hand enters in front of the shoulder, then a slight zigzag path can optimize force and make it possible for a swimmer’s hand to enter and exit the water in line with the side of the body, thereby minimizing twisting of the body.3

Optimal hand path

It is relatively straightforward for a swimmer to maintain the palm facing backward throughout the underwater arm motion. Achieving the optimal hand path of 25° is more challenging. The optimal hand path with respect to the water must be

a Top resultants

As the arm passes under the shoulders, the hand path is backward and angled so that the resultant force is completely propulsive, acting directly forward in the direction of motion. The drag force is directly opposite the direction of the hand path and the lift force is perpendicular (90°) to the drag force. The drag and lift vectors determine the magnitude and direction of the resultant force. Competitive swimmers generally have their palms facing backward during most of the underwater arm motion, to maximize the resultant propulsive force in the forward direction.

64

Technique

25°

Thumb

Pinky finger

70°–75° Hand pitch angle 25° Hand path angle Resultant force

Drag

Lift

Hand path direction

d Forging a path

Hand path relative to the water and the body

The typical hand path of the freestyle swimmer in the left panel is in the shape of an “S.” The hand moves slightly away from the body midline (second image), to the body midline (third image), and away from the body midline again (fourth image). The right panel illustrates the more CH2_SP9_G4_LH_Bl_A gradual changes in direction for an optimum hand path.

12.5° hand path angle, with respect to the body

CH2_SP9_G4_RH_Bl_1

25° hand path angle, with respect to the water

Hand path shape

CH2_SP9_G4_LH_Bl_B

da Relative motion

When considering how the hand moves relative to the water (A), the optimum angle for its path in freestyle is 25° to the midline of the body, but when the frame of reference for the hand movement is the body, the optimum hand path angle is halved to just 12.5° (B). The water resists the backward movement of the hand, so the hand moves less with respect to the water than the body. In the bottom image the blue line shows the hand path with respect to the water and the red line shows the hand path with respect to the body. The hand moves backward about twice as far with respect to the body as it does with respect to the water.

CH2_SP9_G4_RH_Bl_2

CH2_SP9_G4_RH_Bl_3 CH2_SP9_G4_LH_Bl_C

CH2_SP9_G4_LH_Bl_D A

B

CH2_SP9_G4_RH_Bl_4

CH2_SP9_G3

Hand path with respect to the body

Hand path with respect to the water

The blue line shows the hand path with respect to the water and the red line shows the hand path with respect to the body.

65

Why is shoulder impingement the most common swimming injury? Shoulder injuries are prevalent in competitive swimming, even affecting swimmers younger than 10 years old. Most studies over the past 40 years have found that at least one in three swimmers, and in some cases two in three swimmers, suffered shoulder injuries. What’s more, the proportion of swimmers with shoulder injuries is certainly not decreasing. There are three primary risk factors for shoulder injury: harmful technique, overuse, and muscular imbalances (see also pages 156–157). Stretching and strengthening exercises can correct muscular imbalances (see pages 114–115). Moderation of training distance can mitigate overuse. However, swimmers must also carefully monitor their technique and make adjustments to minimize stress. Elevating the arm overhead (as in all four competitive strokes) reduces the space between the bones of the upper arm and shoulder. As a result, the soft tissues between the bones—the tendons and bursa—are compressed. There are a number

What causes my shoulder pain? of typical swimming arm motions that are particularly stressful to the shoulder. Three examples of harmful technique in freestyle are entering the arm with a shallow angle, maintaining the arm parallel to the surface after completion of the arm entry (as in “catch-up” stroke), and internal arm rotation during the recovery. Unfortunately, many swimmers suffer from all three stressful motions. There is no avoiding shoulder stress in swimming. However, there are technique adjustments to minimize both the severity and duration of shoulder stress and reduce the chance of injury. For example, a downward angle on the freestyle arm entry positions the arm below the shoulder at the completion of the entry, to minimize stress severity.1 Immediately beginning the pull after completion of the arm entry minimizes the duration of shoulder stress. Externally rotating the arm on the freestyle recovery also minimizes stress. Protecting the shoulder from injury requires precise control of the arm throughout the entire stroke cycle.

Prevalence of shoulder injuries in swimmers 50

a Shoulder burden

Shoulder injuries are extremely prevalent in swimmers. Even the youngest competitive swimmers are not immune to shoulder injury, as a recent study on 370 injured swimmers showed. The study found that for swimmers aged 11 to 18 shoulder injuries were common, but at ages 19 and above swimmers suffered shoulder injuries more than all other injuries combined.2

45 40 Number of injuries

35 30 25 20 15 10

66

Technique

Shoulder

5

Other

0

11

12

13

14

15

16

17 Age

18

19

20

21

22

23

Shoulder impingement Acromion

a Feeling the squeeze

When the arm is lifted overhead, the subacromial space between the bones of the shoulder and the upper arm becomes squeezed. If this motion occurs repeatedly, as in competitive swimming, over time the compression of the bursa and tendons between the bones causes inflammation and pain. This is known as shoulder impingement.

Clavicle

Swollen bursa Subacromial space

Shallow angle arm entry

Inflamed rotator cuff tendon

Scapula

Humerus Left hand

g Shallow entry These images show a typical arm entry (left arm) that stresses the shoulder. Because the arm is in a weak and awkward position (bottom image), only minimal hand force is generated as pull begins (top image).3

Hand force (N)

110 88 66 44 22 0

Time

Internal arm rotation

Catch-up stroke

g Stress trifecta

This swimmer exhibits three technique elements that stress the shoulders: neck flexion, shoulders submerged deeper than hands, and inward rotation of the arms. Each of these technique elements are independently stressful. The combination of factors produces maximum stress.4

g Playing catch-up

A

B

“Catch-up stroke” is an ineffective arm coordination for freestyle that stresses the shoulder. The right arm in the left image (A) is maintained motionless in front of the shoulder after completion of the arm entry while the opposite arm continues to move to “catch up.” Maintaining the arm entry position increases the “time of exposure” to shoulder stress. In addition, torso rotation (B) further exacerbates shoulder stress.

67

Swim training includes two major areas—skill learning (technique) and conditioning. The training emphasis for younger swimmers is usually on skill learning. Once swimmers become teenagers, the emphasis usually switches to conditioning. This chapter includes information about how to continue skill learning during the teenage years, as well as how to break with conventional wisdom on conditioning. It covers a systematic approach to skill learning, the importance of implementing deliberate practice strategies, helpful and harmful drills, using hand paddles for technique feedback, tips for starts and turns, the trade-off between technique and conditioning, and practice time and distance requirements to develop expertise. There are also sections on how the body adapts to training, overtraining, hypoxic training, high-intensity training, and ultra-short race-pace training.

chapter three

pool t raining Rod Havriluk

Is a systemic approach to skill learning beneficial?

Will standardized coaching improve my technique more quickly?

Swimmers frequently receive different technique instruction when changing teams, and sometimes when changing coaches within the same team. Different instruction regimens are inevitable when coaches choose different top swimmers as their performance models, for there can be dramatic differences in their techniques. (Even casual observers question how such varied techniques can all be optimal!) Yet the conventional wisdom of the swimming culture is to model the technique of each successively faster swimmer, without any scientific analysis or justification. A systematic approach to skill learning standardizes information so that every swimmer on a team, or even within a national federation, receives the same instruction.1 There are three major requirements for implementing a systematic skill-learning system—an optimal model for technique, a coach training program, and what is known as “deliberate practice” (DP). Implementation of a system that includes these components not only standardizes learning so that swimmers receive consistent information, but can also accelerate the learning process, emphasize the technique elements that help avoid injury, and enhance the coaching profession.

A model for optimal technique is based on physics, supported by applied research, and explained with specific cues. Because all humans have technique limitations, a computer-simulated biomechanical model is necessary to help explain aspects of performance. The coach training program should include both this model of optimal technique and learning strategies. Since the conventional practice that coaches are likely to have experienced as swimmers is quite different from the standardized approach, and insufficient to master optimal technique, deliberate practice strategies must be incorporated into training. These include swimmers undertaking a sufficient number of repetitions, staying focused in the cognitive and associative stages of skill learning and replicating superior performance, while coaches must give clear instructions, immediate feedback and individualized supervision, and offer tasks of appropriate difficulty involving a variety of learning strategies. In addition, a regular skills competition is likely to give swimmers the incentive to devote the necessary attention to technique.

On the kick upbeat, keep your feet submerged so only your heels break the surface.

a Training model

Physics principles allow us to develop a model swimming technique that minimizes resistance and maximizes propulsion. Numerous studies on hand pitch, path, speed, and resulting force confirm the model. The graphic represents a computer-simulated biomechanical model of one position in an optimal butterfly stroke. The model minimizes the cross-sectional area of the body that is perpendicular to the direction of movement, which reduces resistance. It also indicates that a 90° elbow angle provides the best leverage (mechanical advantage) for generating maximum propulsion.

70

Pool Training

Area presenting resistance to movement is minimized

Bend elbows to 90° for optimum propulsion As you begin your pull, bend your elbows so your hands pass beneath your shoulders

CH2 SP1 G3 01

Traditional and systematic training comparison Traditional practice,

Traditional, ageto11-12 age 11–12 13–14 to 13-14 (two(two years) years)

Deliberate practice,

Deliberate practice, age 13 age 13 (one(one week) week)

Traditional practice, Traditional, age 13-14 age 13–14 to 15–16 to 15-16 (two(two years) years)

Deliberate practice, Deliberate practice, age 17 age 17 (one month) (one month)

–0.4 -0.4

–0.2 -0.2

00

Improvement in technique (effect size)

o Systematic approach

In contrast to the findings for traditional training, research shows that teenagers treated with a system of instructional strategies improved significantly in a short time. In two other separate studies, DP interventions significantly improved the technique of younger and older teenagers.2,3 Improvement from short-term DP treatments of one week or one month was comparable to that resulting from much longer (two year) periods of traditional training. The DP treatment included the range of DP components as listed in the box on page 73. Swimmers were asked to continually focus on specific visual and kinesthetic cues.

0.2 0.2

0.4 0.6 0.4 0.6 Improvement in technique (effect size)

Freestyle

0.8 0.8

Breaststroke

Freestyle Backstroke

1.0 1.0

Backstroke

Breaststroke

1.2 1.2

Butterfly

Butterfly

71

How does deliberate practice apply to swimming?

What skill-learning strategies should be included in my training sessions?

The “deliberate practice” concept was developed in 1993 by identifying the practice strategies used by top performers to acquire expertise.1 Some of the specific characteristics of deliberate practice that rapidly help to improve swimming skills include those listed in the box on the opposite page. Traditional swim training sessions generally include these strategies to some degree. However, for a swimmer to progress as much and as quickly as possible, all of these strategies must be continuously included in every session. Swim training for younger swimmers typically emphasizes conditioning, with a reasonable level of technique instruction. Many programs concentrate on training distance for teenagers at the expense of continued work on technique. Research shows, however, that both younger and older teens can benefit from even short-term instructional interventions that include deliberate practice strategies.2,3 There are numerous reasons why swimmers do not practice deliberately. With a typical emphasis on conditioning, swimmers are often swimming fast, and with fatigue, during a considerable portion of each training session. Speed and fatigue make it very difficult for a swimmer to focus on specific technique elements to make sure they are replicating superior performance. Even when swimming at a relatively slow pace, swimmers are likely to lose focus on technique (that is, not maintain attention in the cognitive and associative learning stages of Bloom’s taxonomy) and instead rely on “automatically” processing each stroke cycle (switching to the autonomous or psychomotor learning stage). There are also distractions that make it difficult for a swimmer to practice deliberately. There are often five or more swimmers in each lane so that it is a challenge to focus on technique while avoiding other swimmers. Usually, there are also a number of conditioning instructions that a swimmer must process, such as maintaining a certain pace, heart rate, or intensity level. 72

Pool Training

But a detailed understanding of how deliberate practice components apply to swim training can improve the use of these learning strategies. For example, deliberate practice conducted in a small pool, rather than a busy training facility, is perfect for adjusting the task difficulty to match the swimmer’s ability level—the swimmer is limited to a small number of strokes, minimizing fatigue and increasing the opportunities for feedback. A mirror placed on the pool bottom provides visual feedback even in solo practice.

Comprehensive strategies Classroom instruction Explain optimal technique using a model Identify critical motions and positions Specify technique elements with cues to see and feel

Pool instruction Review selected cues Practice with short, slow, non-breathing swims Repeat drills that isolate technique elements

Classroom analysis Reinforce positive technique elements Identify limiting factors Make comparisons with model

Pool testing Collect data on stroke rate, stroke length and swim velocity Capture video and force data Process information for immediate feedback

o Variety of learning strategies Much of the time, instruction and testing are conducted at the pool (blue arrows). A more comprehensive treatment includes classroom sessions for instruction and analysis (red arrows).4

Line weights_white lines faces .5pt Line weights_white lines onon faces .5pt CH3_SP2_G1 CH3_SP2_G1 Line weights_white lines faces Line weights_white lines on on faces .5pt.5pt Model technique

Characteristics of deliberate practice • clear instructions • appropriate task difficulty • a sufficient number of repetitions

As you complete your arm entry, straighten your arms in front of and below the shoulders.

When not breathing, keep your head motionless with the water level at the top of the head.

As you begin your pull, bend your elbows so that your hands pass directly beneath your shoulders.

On the kick upbeat, keep your feet submerged so that only your heels break the surface.

When breathing, keep your chin under water.

As you complete your push phase, touch the front of your thighs with your thumbs.

As your arms recover, keep your thumbs just above the water.

As your arms recover, keep your elbows higher than your hands.

• solo practice with and without a coach • immediate feedback • a variety of learning strategies • maintaining focus in the first two learning stages (cognitive and associative) • replicating superior performance

a Clear instructions

Images of a biomechanical model demonstrating optimal technique help to make instructions very clear. It is vital to include visual and kinesthetic cues with the model to specify body part orientations and motions.

Hand force after deliberate practice Hand force (N)

a Short and sweet The bar graph on pages 70–71 shows that improvements in technique following short-term deliberate practice treatments are comparable to those resulting from much longer periods of traditional practice.2 The specific example illustrated here supports these findings—the force curves for a 14-year-old male backstroker show that after a one-week deliberate practice treatment his peak hand force doubled.3

145

Left Hand

Right Hand

116 87 58 29 0 Before deliberate practice

After 1 week of deliberate practice

73

Will 10,000 hours of practice make a swimmer an expert?

Will hours of practice perfect my technique?

Some sources consider that 10,000 hours of practice is a necessary minimum to develop expertise in any field.1 While a landmark study on deliberate practice by Ericsson, Krampe, and Tesch-Römer2 is often cited, these researchers did not find that 10,000 hours was necessary, nor that 10,000 hours would guarantee achieving an expert level of performance. They did find that, in a number of fields, experts typically accumulated at least 10,000 hours of practice. However, depending on the activity, experts had practiced from 2000 hours (for memorizing strings of numbers) to 25,000 hours (for playing the piano in concert).

a Building up

Based on a training progression by the former CEO of Australian Swimming Dr Ralph Richards, swimmers accumulate almost 10,000 practice hours by the time they are older teenagers.5 The LTAD (Long Term Athlete Development) model used in English swimming (up to age 19) proposes similar accumulated practice hours to the Richards model.6

Cumulative practice (hours)

For many activities, the accumulated practice hours may have more to do with the normal progression of training programs as opposed to a plan designed to develop expertise. Children often become involved in an activity like swimming at a young age (8 years old or younger, for example). Practice sessions for beginners are typically one hour, yielding two or three hundred hours of practice per year. Preteens often train about 500 hours per year and teenagers as much as 1000 12,000 hours per year. Many swimmers practice 10,000 hours by the time they finish high school, but 10,000 they do not necessarily achieve an expert level of performance.

Swimmers generally benefit physiologically from their training hours and achieve considerable expertise in conditioning. Research shows, however, that many practice hours are not sufficient to produce technique mastery. The results of a recent study3 showed that, during most of a typical training session, swimmers focus on conditioning and not on technique—which suggests a possible reason why technique expertise is not always achieved, despite long hours of practice. Swimmers have a variety of distractions that interfere with their focus during a training session, including watching the pace clock, avoiding collisions with other swimmers, and monitoring effort and pain levels. A normal team training environment is quite different from the “solo practice” found to be essential for deliberate practice.4 Because of the difficulty in focusing during a team session, swimmers desperately need solo practice in order to perfect technique.

Training progression and long-term development

8000

6000

4000

2000

Richards’ training progression5 LTAD model used by Amateur Swimming Association (ASA) in England6

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6

7

8

9

10 11 12 13 14 15 16 17 18 19 20 21 Swimmer age (years)

Annual training hours for champion athletes

istance runner

Distance runner

ienteer

Orienteer

country skier

g Putting in the hours

This chart shows the representative peak annual training (in hours) for champion athletes from different sports. Ballistic and eccentric loading differences, demands on technical entrainment, and non-specific training distance may all contribute to the differences.7

Cross-country skier

Rower

Rower

Cyclist

Cyclist

wimmer

Swimmer 200 400 600 800 00 200 400 600 800 Annual training hours Annual training hours

1000 1000

1200 1200

1400 1400

CH3_SP1 G2 01

d Diminishing returns Research shows that teenagers do not continue to improve their technique (as measured by the drag coefficient, Cd, where a lower Cd indicates a more effective technique), even with many more thousands of practice hours. A cross-sectional analysis provides a view of the technique trend for traditional training. The graph shows data on eight groups of freestyle swimmers of different ages, demonstrating a dramatic improvement in technique (drop in Cd) from the 9–10 age group to the 11–12 age group.8 However, the improvement to the 13–14 age group is much more modest, and there is no further improvement evident during the teenage years. These findings are perhaps unsurprising considering the increase in training distance and conditioning, and decrease in technique instruction, typical in traditional training regimens for teenagers. This is illustrated in the table, which compares the number of swimmers focused on technique, as opposed to other factors, in each phase of a training session.3

Traditional training

Female freestyle swimmers

1.4

1.4

1.3

1.3

1.2

1.2

1.1

1.1

1.0

1.0

0.9

0.9

0.8

0.8

0.7

0.7

99–10 - 10 Age group

11–12 11 - 12

13–14 13 - 14

Age group

15–16 15 - 16

Swim training focus

1.5

17–18 17 - 18

Phase of training session Active drag coefficient, Cd

Active drag coefficient, Cd

1.5

Male freestyle swimmers

Swimmer focus Technique

Warm-up 5

Main sets 0

Cool-down 1

Conditioning

3

10

2

Technique and conditioning

1

3

0

Other

9

5

15

TOTAL

18

18

18

Male freestyle swimmers Female freestyle swimmers

75

equipment: hand paddles

However, improving technique is far more complicated than just wearing a piece of plastic on your hands. There is no research evidence that an improvement in technique can be achieved by training with a specific paddle design. The paddle goes where the hand takes it, not the other way around. Although there are creative paddle designs that limit motion in non-productive directions, only future study will determine their benefits. The strength-training benefits of paddles depend largely on a swimmer’s awareness of hand speed. If a hand paddle increases the area of the swimmer’s propulsive surface, and the swimmer moves the hand with the paddle at the same speed as without the paddle, the swimmer will generate more propulsion. However, because of the larger surface area, a swimmer will naturally move the hand through the water more slowly with the paddle than without at first. The strength-training benefit depends on the swimmer gradually increasing the hand speed when wearing paddles. Hand paddles are sometimes blamed for causing shoulder problems. Generally, a swimmer’s technique is to blame and not the paddle. Once a swimmer has a shoulder injury, wearing paddles can aggravate it. However, because paddles provide such exact feedback, they can also be the best way to modify technique, reduce shoulder stress, and recover from an injury. 76

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500

Left hand Right hand

400 Peak hand force (N)

Paddles are the one essential piece of training equipment. While often thought of as strength training equipment, paddles are also extremely valuable for improving technique. Paddles slow the hand speed and make it easier for a swimmer to track the hand path while it is within the field of view. When the paddle moves out of the swimmer’s view, the size and shape make the pitch of the paddle more obvious. The enhanced feedback provides a swimmer with precise information for improving technique.

300

200

100

0

Hand only

Flat paddle

3D paddle

o Strength-training with paddles The graphs show hand force data for two cycles on trials in which a swimmer wore concave-shaped (3D) paddles, flat paddles, or no paddles at all. When using 3D paddles the swimmer is hitting peak force with the left hand at the end of the push phase. The peak force values were similar for bare hands and flat paddles, but about 50% higher for the 3D shape paddles. The consistency was remarkable, as the values for the 3D shape were higher than the flat paddles for both the left and right hands for every subject.1 The results suggest that the unique paddle design could lead to improved strength.

C_2G_A3PS_3HC tcejbo depuorg elddap hcae

d Bright colors make it easier to see the exact orientation (pitch) of the paddle.

CH3_SP3A_G2_A

g a Paddles to highlight technique

A hand paddle is basically a flat piece of plastic, with about twice the surface area of the swimmer’s hand. A finger strap over the middle finger and, generally, a wrist strap hold it in place. Paddles cannot prevent a swimmer from performing ineffective technique elements, but they provide invaluable feedback to the swimmer and coach, so that issues can be analyzed and addressed. CH3_SP3A_G2_G_1

3D paddles are giving CHconcave, 3 a cupped shape _asSP the 3Ahand _G2 moves through the water. _G_2 Avoid gripping the sides of the paddle.

F

CH3_SP3A_G2_

Place the fingers flat on the paddle surface.

d Paddles without wrist straps

d Some paddles are designed to help with specific technique elements, such as excessive lateral motion (above). The perpendicular blades on the underside of CH3_SP3A_G2_H the paddle restrict sideways movement.

Paddles without wrist bands provide feedback about the effectiveness of the exit phase—during butterfly or freestyle, if a swimmer has an effective hand orientation (with the pinky finger pointing upward), the paddle will stay on the hand (A), but if the swimmer has an ineffective hand orientation as the hand exits the water (with the back of the hand facing upward), the paddle will typically come off (B).

CH3_SP3A_G2_D

CH3_SP3A_G2_J _1

CH3_SP3A_G2_J _2

A

CH3_SP3A_G2_E

1_ L_2G_A3PS_3HdCThis paddle is intended to give the

2_ L_2G_A3PS_3HC

swimmer feedback about the classic “dropped elbow,” by providing more CH3_SP3A_G2_K resistance if the elbow moves backward in the same horizontal plane as the hand.

Correct technique

B

Wrong technique

77

What is the optimal training distance?

Is it necessary to swim so many laps?

The swimming culture generally emphasizes quantity over quality when it comes to training distances. A recent study cited mega-yardage values in the 1970s, in excess of 100,000 yd (90 km) per week, with current distances ranging between 60,000 and 95,000 yd (55–87 km).1 Former Olympic coach Gregg Troy has a “rule of thumb” of 76,500 yd (70 km) per week.2 The fact that many programs have been extremely successful with considerable or even excessive training distances has served to reinforce this trend.

There are physiological guidelines that can help a coach determine the most appropriate training distance. For example, the duration of the majority of individual events for many swimmers is about 2 minutes or less. Since the majority of the energy contribution is anaerobic for events of relatively short duration, it makes sense to train the appropriate energy system. The ability to endure a 10,000 yd (9 km) training session has very little to do with swimming fast in most events. In addition to the physiological basis of training, there are also anatomical, biomechanical, and skill-learning issues to consider in determining the most appropriate training distance.5 Development of an optimal training plan must address speed and conditioning issues, but also consider factors such as the health, strength, and technique of the swimmer. There are swimmers that excel by training great distances. This does not, however, confirm that considerable training distance is optimal.

There are, however, vastly differing views on appropriate training distance. For example, Dave Salo, another former Olympic coach has “not focused on yardage in 30 years.”3 In the early years of his career “everything was about yardage … building up to 9,000–10,000 yd (8–9 km) a workout,” but he found that “the kids were miserable, and I was miserable.” With a similar approach to training distance, Brent Rushall developed Ultra-Short Race-Pace Training (USRPT) to emphasize competition speed and not total training distance.4

Training distance plans

80

12-week training 15-week training

a All in the plan

Training plans typically increase distance over several weeks or months and then decrease distance during the taper phase before the most important competition of the season. In the two plans shown here, there is considerable difference in the peak weekly distances. Some training plans anticipate the need for recovery weeks with a reduced training distance.

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Weekly training distance (km)

70 60 50 40 30 20 10 0

1

2

3

4

5

6

7 8 Week

9

10

11

12

13

14

15

Benefits of a reduced training distance6 • fewer stroke repetitions decrease the chance of shoulder injury • less fatigue makes it easier to maintain focus on technique

d Power surge The contributions of anaerobic and aerobic energy systems change depending on the duration of exercise. Swimmers mostly race distances of 200 m or less, so the time they spend swimming is usually less than two minutes. Performance in these events is more closely related to power (anaerobic energy) than endurance (aerobic energy). Anaerobic

• more time for coach–swimmer interaction • more time for technique analysis • more time for race-specific practice

Power and endurance

Aerobic

100 90 80

Percent of energy contribution

70 60 50 40 30 20 10 0

2

4

6

8

10

12

14 16 Exercise duration (min)

18

20

22

24

26

28

30

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Which skill-isolation drills are most beneficial?

Do some drills do more harm than good?

While there are a number of drills that are extremely helpful for improving technique, simply performing a drill does not guarantee an improvement. Some drills are at best a waste of time, while some can be counterproductive or even harmful. In evaluating a swim drill, it is most important to determine if the drill replicates effective technique. A productive drill isolates part of a stroke so that a swimmer can focus on specific technique elements.1 Counterproductive drills distort the body from the normal swimming position, reinforce ineffective positions or movements, and can cause joint stress. There are numerous popular drills for freestyle. Unfortunately, many of these drills, such as “kicking on the side” and “onearm freestyle” are counterproductive because they reinforce an ineffective arm position and stress the shoulder. “Catch-up” drill (see pages 52–53) is also detrimental, as it has similar negative effects. What’s more, extensive research has shown that fast swimmers (or swimmers trying to go fast) do not use “catch-up” arm coordination, so practicing “catch-up” is counterproductive from a skill-learning perspective.2 Butterfly drill

For most skills used in the unilateral strokes (backstroke and freestyle), swimmers can progress much faster by focusing on specific technique elements within a normal stroke cycle, rather than using skill-isolation drills. For example, a swimmer can continually evaluate head position and arm orientation at critical checkpoints, using visual and kinesthetic cues. Some swim drills are not necessarily harmful, but are not helpful either. For example, the breaststroke “three-second glide” drill (where a swimmer maintains the streamline glide position after each stroke) presumes that a swimmer will focus on the streamline for three seconds. In reality, it is much more likely that a swimmer will simply rest for the three seconds. There are some drills for the bilateral strokes (breaststroke and butterfly) that can be extremely beneficial. Helpful breaststroke and butterfly drills isolate either the arms or the legs while maintaining bilateral symmetry—a swimmer can better focus on arm technique elements when there is no head, body, or leg motion. Breaststroke and butterfly drills are also useful in minimizing vertical head and body motion when breathing.

1

2

3

1

2

3

Front view

Side view Breaststroke drill Front view Top view

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Visual and kinesthetic clues Kinesthetic

Kinesthetic Freestyle

Breaststroke Visual Visual

Visual Kinesthetic

Butterfly

Backstroke Kinesthetic Visual

o See how it feels Most freestyle and backstroke drills distort the body position. To improve techniques in these strokes, it is much more expedient to focus on specific visual and kinesthetic cues—specific body part orientations that a swimmer can see or feel during the stroke. Although a swimmer has a very limited range of the stroke cycle within the field of view in all four strokes, it is possible to see the elbow bend as the arm

passes the shoulders and the hand passes beneath the head in freestyle (top left)—to assess and modify arm technique during the rest of the cycle, the swimmer relies on kinesthetic cues. In backstroke, the swimmer can see the arm above the surface in line with the side of the body, and feel a 90° bend at the elbow in the lower arm (bottom right). In all four strokes, kinesthesia provides most feedback on technique.

Effective butterfly and breaststroke drills

d Drilling down Some drills for the bilateral strokes can be extremely effective. In these breaststroke and butterfly arm drills, the head, body, and legs are motionless, which makes it easier to control and focus upon the arm motion.

4

5

6

4

5

6

81

SCIENCE

IN ACTION

ultra-short race-pace training (USRPT)

Traditional swim training emphasizes conditioning with total training distance as the most important factor. More recently, some coaches have placed a greater emphasis on quality instead of quantity. Ultrashort race-pace training (USRPT) is one method that emphasizes quality and has promoted the shift in training emphasis.1 The success of one swimmer in particular, Michael Andrew, has encouraged more coaches to try USRPT or at least downplay the quantity of training distance in favor of a greater emphasis on quality. USRPT was introduced by Dr Brent Rushall in 2011. His training method is fundamentally different to other types of “quality” training in that a quality effort on each swim is not just specified (as a pace for a given race), but required. In a typical traditional training set, swimmers are given parameters according to the acronym DIRT—distance, interval, repetitions, and time. For example, a set might be 20 repetitions of a distance of 50 m on an interval of 50 s, holding a time of 30 s for each swim. (The interval includes both the swim time and rest time.) If a swimmer does not swim the specified distance in the specified time, he or she has less rest before pushing off for the next repetition, but will often receive encouragement from the coach, and can usually continue to produce a substandard level of quality with no modification of the training set (DIRT) parameters. USRPT is different. If a swimmer is unable to swim a repetition at the required level of quality (as indicated by performance time), he or she rests during the next repetition (in this example, for 50 s). The rest will usually make it possible for the swimmer to recover enough to achieve the required performance time on the next repetition. If the swimmer achieves the required performance time, he or she can continue with the set. If the swimmer fails to achieve the required performance time on two successive attempts, he or she must terminate the set. The USRPT guidelines, therefore, assure that swimmers will benefit from substantial practice using race-specific velocity and technique.

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a Quality focus

Michael Andrew in the men’s 100 m butterfly during the Arena Pro Swim Series at Austin, Texas on January 15, 2016. Andrew credits his phenomenal swimming success largely to USRPT. Instead of swimming around 12,000 yd (11,000 m) in traditional training each day, much of which could be called “junk yardage,” Andrew swims just 2500– 3000 yd (2285–2740 m) daily, focusing on race pace and perfecting technique.

What is the physiological adaptation process?

Generally, the emphasis at the beginning of a swim season is on aerobic conditioning. The physiological responses include increases in heart, lung, and blood volume. Because the heart is larger, it can pump more blood with each beat—that is, the stroke volume increases. This of course means that, at a given heart rate, the volume of blood pumped per minute—the cardiac output—also increases. (And at a given cardiac output, the heart rate will be lower.) The increase in lung volume allows oxygen to enter the blood and reach the muscles at a higher rate. The increase in blood volume raises arterial blood pressure. The net result is an improved capacity for work. Strength training (whether performed on land or in the water) is a vital component of swim training and is somewhat in conflict with endurance training (see also pages 74–75). The most obvious difference is the number of repetitions performed to optimize each regimen. The endurance emphasis in swimming typically involves tens of thousands of stroke repetitions. Strength training typically involves sets of only ten repetitions of an exercise. Fortunately, research shows that the benefits of endurance training are not compromised, and can be enhanced, by concurrent strength training.1 The effect of strength training is to produce muscle hypertrophy (bigger muscles) that can generate more force. While the cross-sectional area of the muscle is the best indicator of muscular strength, the neural component is also important.2 84

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Neural adaptations involve more motor units (muscle fibers and the nerve cells that serve them) being recruited, or activated, at once. Put simply, if the training stress is not sufficient to overload the body, then there will be no physiological adaptation—that is, the body will not change. If a training stress is too great to be tolerated, then the body will be injured, or over-training will occur.3 Swimmer performance must be carefully monitored during each training session so that adjustments can be made as necessary. A coach will often use a standard training set— for example, a set of 100 yd or 100 m freestyle swims on a given interval—to monitor swimmer adaptation.

Stimulus training Stimulus—training session Super-compensatory adaptation —fitness gain

Fitness level

A basic objective in training is to elicit a response that improves performance. To accomplish that goal, swim programs generally have an increase in workload in the beginning of the season, a hard-training phase in the middle, and a decrease in the workload at the end (that is, a taper). The increase in workload is usually controlled by varying the training distance and intensity. At the end of the season, there is the expectation of a performance improvement due to the taper (see also pages 90–91).

How does my body adapt to training?

Fatigue

Compensation (recovery)

Recovery time between training sessions

Stimulus 2

Stimulus 3

CH3_SP6_G2

Muscle hypertrophy (growth) Increased simultaneous recruitment of motor units More fatigue-resistant slow-twitch muscle fibers

Physical adaptations 2 Respiratory adaptations

1

Better oxygen uptake in lungs Improved blood flow through lungs Reduced submaximal respiratory rate

The body adapts in response to the frequency, intensity, duration, and specificity of training. However, a law of diminishing returns comes into play, because as training progresses, incremental gains become smaller, so the level of overload must be constantly increased to continue to achieve benefits. The graph shows how neural and muscular adaptation improve with repeated training over time, and then plateau. Muscular adaptation includes the growth in cross-section of muscles, while neural adaptation involves improvements in the number of motor units (muscle fibers) that can be stimulated at once. The summed effects of improvement in both the nervous and muscular systems contribute to a swimmer’s increase in strength.4

Stimulus 5

3

4

3 Cardiovascular adaptations

a Making changes

Stimulus 4

2

Progress

1 Neuromuscular adaptations

Time Strength Neural adaption

Increased cardiac muscle mass and chamber volume, causing increased stroke volume and cardiac output Increased blood volume, red blood cell density and hemoglobin concentration Faster diffusion of oxygen and fuel into muscles

Muscle growth

4 Muscular adaptations More blood capillaries in muscles Increase in size and number of mitochondria—the “energy factories” in cells Increased myoglobin concentrations, which aids oxygen delivery to muscle fibers

Increasing fitness and performance

g Cumulative gains Time

Optimal Inadequate stimulus Insufficient recovery time or stimulus too great

The training adaptation cycle includes a training stimulus (overload), fatigue, and recovery, during which stressed tissue heals and muscle tissue grows, and super-compensatory adaptation, resulting in increased fitness and performance relative to the initial baseline level. Repeated training sessions with appropriately increasing workloads produce cumulative effects over time. Optimum workouts provide a maximum training effect—if the workouts are too easy, the swimmer will not build the optimum fitness gains, while if they are too hard, recovery may not occur before the next session, and the swimmer’s fitness will decline over time. The recovery interval between training stimuli is also important—if the swimmer trains again too soon, muscle tissues will not be adequately recovered, but if the new stimulus is left too late, fitness levels will return toward baseline and the gains of adaptation will be lost.

85

How do swimmers respond to extreme overload? It is a real challenge for a coach to design a training program that provides the appropriate overload. Even the most conventional training plan can have a variety of outcomes depending on the training load, swimmer effort, and many other factors. For this reason, it is essential to periodically monitor swimmer response to training load to avoid overtraining, as the consequences of this can include a drop in performance, injury, or even illness. Unfortunately, overtraining is common in swimming. In one study of competitive swimmers, 50% were classified in maladaptive (overtrained) categories.1 In another study, almost one-half were overtrained.2 Data from 30 studies show that over 50% of swimmers suffer from shoulder injury, where excessive training distance is a primary risk factor. Preventing overtraining requires tracking specific variables. A wide range of physiological, psychological, medical, and performance tests have been used, because a single factor is insufficient to reliably quantify likelihood of overtraining.3 Coaches strive to overload their swimmers so that, after a recovery period, “super-compensatory adaptation” produces

Should I always train hard? enhanced performance (see pages 84–85). When the overload is excessive, however, swimmers may react in very different ways. In some cases, swimmers may consider even extreme soreness as part of the adaptation process and continue training, which could result in a cumulative drop in fitness if further training occurs before the swimmer has recovered properly. In other cases, muscular fatigue may self-limit continued training and cause a swimmer to swim slower.4 Tracking data about how swimmers respond to training is essential so that adjustments can be made to ensure an optimal result. An adjustment in training load may be the most obvious response, but rest, nutrition, and hydration are other important factors to consider. Attaining an adequate amount of rest is difficult for a competitive swimmer who has two training sessions on most days. Swimmers often train for two hours without any substantial nourishment, where some replenishment is usually required after one hour. While “train hard” is a common and necessary mantra in sports, it is also essential to carefully monitor the athlete’s response.

Burnout zone

g Avoiding burnout

Training causes fatigue, inevitably, but programs must be engineered, based on response data from swimmers, to ensure that recovery and super-compensatory adaptation can occur. There is a danger of overtraining and failing adaptation, if a swimmer trains “too hard” without sufficient recovery. Here, Swimmer A trained “moderately hard,” recovered from fatigue, and had a successful adaptation. Swimmer B trained hard enough to be close to failing adaptation, but was able to recover with a reduced workload, and achieved extreme adaptation. Swimmer C worked so hard that he went into the failing adaptation zone and even with rest and reduced work was not able to return to the normal adaptation zone.5

A B

Extreme adaptation zone Super-compensatory adaptation zone

C

Fatigue zone Time during daily training regime

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Failing adaptation zone (maladaptive)

Workload studies 10

5

Variation in average force (%)

0

–5

–10

–15

–20

–25

–30

Early (baseline)

Middle (heavy workload)

Late (taper)

Seasonal testing date

o Pushing too hard

Nine national-caliber swimmers from a team known for training with a substantial workload participated in a study2 and were tested seven times over an eight-month season. In preparation for the major competition at the end of the season, coaches taper swimmers—gradually reducing their workload so the swimmers can rest and recover. The muscles hypertrophy and are then capable of generating more force. The average hand force over a 10 m swim at maximum swimming velocity was calculated for each trial. The graph shows that each swimmer had a depressed hand force value in the middle of the season as compared to the baseline at the beginning of the season. Each swimmer’s force value was elevated at the end of the season as compared to the middle of the season. However, only five of the nine swimmers (55%) had a higher force value at the end of the season as compared to the baseline. The swimmers whose force values were depressed by about 10% during the heavy workload were able to recover and generate more force after the taper than at the beginning of the season. The swimmers whose force values were depressed by about 20% were not able to recover after the taper. The results suggest that a workload that is too severe (because of training distance or intensity, or both) may not allow swimmers to recover enough to improve performance.

Female swimmers with lower force value Male swimmers with lower force value Female swimmers with higher force value Male swimmers with higher force value

NEED TO KNOW Tapers at the end of a season can vary from less than one week to more than three weeks, primarily depending on workload, event, and individual differences.

87

What is high-intensity training?

Should I vary my effort level and training distance?

Since the late 1960s, there has been an emphasis on training distance in swimming. “This ‘aerobic-base’ concept has flourished in all endurance sports and in reality is still the dominant swimming coaching philosophy applied in most parts of the world.”1 However, while the trend for many programs is still to have swimmers train substantial distances, some coaches have found success with less distance and more intensity using high-intensity training (HIT). Ultra-short racepace training (USRPT) is an example of a HIT program (see pages 82–83). Even though swimmers are using training distances that are only 50% of traditional programs, such programs are still considered “very hard.”1

distance or frequency, was correlated with improvement for a group of elite swimmers.4 The findings of a fourth study suggested that swim programs should alter their approach to emphasize increased intensity quality, over low-intensity quantity.5 The effect of a HIT program on technique is important to consider. If a swimmer is mostly training at fast speeds, he or she may not be able to control specific technique elements. A swimmer must swim many thousands of strokes at a slow stroke rate to effectively monitor and control technique. After mastering a technique element, a swimmer must gradually increase stroke rate to racing speed over many more thousands of strokes. The strategies necessary to improve technique require caution in the amount of HIT in each training session. A recent review summarized that “the current evidence on the effects of HIT on performance is promising; however, it is difficult to draw accurate conclusions until further research has been conducted.”6

Mean 2000 m time (s)

Much research supports the effectiveness of HIT. For example, a study that applied a high-velocity training regimen to a group of university swimmers over four years found a 10% and 8% performance improvement in the 100 and 200 yd (≈ 100 and 200 m) freestyle, compared to a 1–3% range of improvement reported for more traditional programs emphasizing training distance.2 Another study showed that high-intensity flume training significantly improved swimming Test—time performance in a pool over 100 and 400 m.3 before HIT 2175 A third study found that intensity, but not training

Test—time after HIT

2150 2125 2100 2075 2050 2025

–4 –3 Time (weeks) 2.5 weeks break

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–2

–1 Pre-conditioning

0

1

2

3

4 HIT

5

6

7

Improvements for long and short distance Post HVT treatment

a No loss

In one study, masters swimmers underwent a six-week period of conventional high-volume, low-intensity training, and then a similar period of high-intensity, low-volume training.7 After the high-volume treatment, there was significant increase in maximum oxygen uptake, and significant improvements in 400 and 2000 m performance. After the subsequent highintensity treatment, there was a significant improvement in 100 m performance without a loss of the other improvements.

12

Percentage improvement (%)

10

d Taking the HIT The graphic shows an experiment where two groups of swimmers underwent both high-intensity (HIT) and high-volume (HVT) treatments.8 One group underwent HIT first, then HVT after the break. At the same time, the other group started with HVT, then swapped to HIT. The training distance for HVT was double the distance for HIT. The tests before and after each five-week treatment involved several metrics, including each swimmer’s time over 2000 m. When the results for both groups were pooled, a significant improvement in the average (mean) 2000 m time was found after the HIT treatment. There was a much smaller improvement from the HVT treatment, which was not statistically significant. This study is important for two reasons—first, it shows that swimmers can train for less time and achieve as good or even better results, and second, it shows an experimental design where all participants are subjected to both treatments.

8

6

4

2

0

HIT versus HVT training

Post HIT treatment

2000 m 400 m performance performance

VO2 max

100 m performance

Test—time before HVT

Test—time after HVT

2175 2150 2125 2100 2075 2050 2025

8

9

10 6 weeks break

11

12

13 Re-conditioning

14

15

16

17

18

19

20

21 Time (weeks)

HVT

89

What is the trade-off between conditioning and technique in a season plan?

Having set the plan at the start of the season, each day a coach is then faced with decisions about what activities best fit the plan. Each training session presents issues such as swimmer tardiness, absence, illness, injury, soreness, fatigue, lack of motivation, or conflicts with other activities, which may make it necessary to deviate from the original plan. When this happens, the pressure of the competition schedule and a typical emphasis on conditioning often mean that work on technique is sacrificed.

Coaches can use deliberate practice strategies to increase the distance over which swimmers maintain effective technique (see pages 72–73), if they are willing to stop swimmers if they do not maintain control of specific technique elements.1 Coaches can track the distance for which a swimmer maintains effective technique (deliberate practice distance or DPD) compared to total training distance (TTD). The trade-off between DPD and TTD requires coaches to consider whether it is better to practice a longer distance with a less effective technique or a shorter distance with a more effective technique.

Evaluating data 1.40

210

200

1.36

190 1.32 180 1.28 170 1.24

160

a Balancing act

This chart shows the change in stroke length for a group of swimmers over a set of eight 100 m freestyle swims.2 The swimmers maintained a very similar swim time for each repetition. However, by the last two swims, their stroke length had dropped so much that they were averaging two extra strokes per 25 m. Based on these results, it might make more sense in future for the swimmers to swim only 6 × 100 m, so that they can maintain their stroke count (that is, their technique).

90

Pool Training

1.20

1

2 3 5 6 7 4 Number of 100-m freestyle swims Stroke length

8 Heart rate

150

Heart rate (beats per minute)

A season plan is usually based around the season-ending meet (for example, a championship event), but may also take into account interim competitions. For older, more competitive swimmers, there may be little alteration in the plan for any interim competitions, while for younger, less competitive swimmers, there may be an adjustment for every interim meet. Some top competitors develop a four-year plan focused on Olympiads, as opposed to a single season or year plan. It is common to plan for both a longer time frame (a macro-cycle) and interim shorter time frames (micro-cycles). Within each cycle, a coach also plans how to vary different training activities, such as technique and conditioning. The overarching concept determining a season plan is how the workload—the training distance and intensity combined—is varied week by week, according to the competition schedule, to optimize performance.

Even when conscientiously trying to maintain effective technique, conditioning demands of speed and effort make it difficult for swimmers to stay focused.

Stroke length (m/stroke)

The typical question asked about any training session is “how far did you swim?” Rarely is a question posed about how far you swam at race pace for a given event, or how far you swam focused on specific technique elements.

How do you plan training for a whole season?

Varying training distance Month Short-course season (25 m laps)

Jan

Long-course season (50 m laps) Transition phase (competition)

Feb Mar

a Plan for success

Weekly training distance often varies considerably from week to week as swimmers taper to prepare for major competitions. During taper, training distance is often reduced to about one-third of peak distance. This chart, designed for masters swimmers (19 years and older training with a less formal group), shows a one-year plan involving three major championships in May, August, and December.

Apr May Jun Jul Aug

d Going the distance

A season plan usually includes a breakdown of the emphasis on activities and energy systems, but the training distance is generally the most prominent value. This is an example of a plan for elite swimmers. Depending on many training factors, it may be appropriate to use periodization, where a season plan is divided into smaller cycles.

Sep Oct Nov Dec 6

0

12 Weekly training distance (km)

24

18

Season plan for elite swimmers

Weekly training distance (km)

Endurance

Taper

Prep

Endurance

Specific endurance

Anaerobic

Nationals

Grand Prix

Grand Prix

Grand Prix

Grand Prix

Dual meet

Nationals

Grand Prix

Invitational

Dual meet

Meets

Month Sep Oct Nov Dec Jan Feb Mar Apr May Jun Jul Aug Week 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 1

Mixed

Taper

Transition

Prep

100 90 80 70 60 50 40 30 20 10 0

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What is hypoxic training?

How should I control my breathing?

Hypoxic training involves depriving swimmers of an adequate oxygen supply with the intent of improving physiology and performance. There are a number of ways that coaches reduce swimmers’ oxygen supply—altitude training, using a hyperbaric chamber, underwater swimming, and swimming at the surface with a controlled breathing frequency, the last of which is the most common method. Breathing frequency is controlled during training swims in two ways—either by setting the number of stroke cycles between breaths, or by setting the number of breaths per length of the pool. Altitude training is generally possible for only a small percentage of competitive swimmers. Although the scientific evidence in support of altitude training is scarce, and its benefits are controversial,1 a recent study found that a fourweek treatment of altitude training did indeed produce a performance improvement in elite swimmers after a recovery period at sea level.2

on a stroke or during the turning motion at the wall. In each of these cases, the breath control is related to technique and performance, as opposed to a physiological training effect. During a non-breathing stroke cycle, there is no need for the swimmer’s head to move. If the head is static with respect to the body, a swimmer can be more certain of how other body parts are being controlled, for better focus on technique. In addition, less head motion is likely to result in less distortion of the body, and therefore less resistance. Another benefit of less body distortion is that the body is in a more stable position to generate propulsion.

NEED TO KNOW Some key terms: Hypoxic—Deprived of adequate oxygen supply Hyperventilation—Rapid and deep breathing Hypoventilation—Inadequate ventilation

Regardless of whether hypoxia and controlling breathing frequency have physiological advantages for swimming, there are definitely technique advantages, and swimmers often control their breathing pattern for a performance benefit when racing. For example, swimmers often take a breath on every second stroke in butterfly, or on every third stroke in freestyle. In breaststroke, some swimmers occasionally do not breathe

Hypercapnia—Elevated level of carbon dioxide in the blood Apnea—Temporary cessation of breathing Blackout—Loss of consciousness

Butterfly breathing Non-breathing position

WARNING Holding your breath can be extremely dangerous, possibly resulting in blackout and death. It is recommended that swimmers breathe when necessary and only practice breath-holding activities under the close supervision of a swimming professional.

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During a non-breathing cycle in butterfly, the body maintains a level position, minimizing resistance.

CH3_SP10_G2_A

Freestyle breathing

a Breathe easy

When swimming freestyle with an optimal non-breathing head position, the water level is at the hairline. The swimmer can then breathe with minimal head rotation. Note that, during the breath, only one goggle is above the bow wave and that only part of the mouth is visible.

Non-breathing position

Head is still and looking down toward the pool floor.

Blow out

CH3_SP10_G2_B Effective breathing position

d Butterfly breath It is difficult to Swimmer is rotating her head to breathe through her mouth. Just one breathe less frequently than on every goggle is above the bow wave and only part of the mouth is visible. stroke when swimming butterfly. CH3_SP10_G2_C However, breathing less often (for example, every two or three strokes) can help a swimmer maintain a fairly level body position on the non-breathing stroke Ineffective breathing position cycles, and reduce resistance. On a breathing stroke cycle, some swimmers appear to be desperate for air, and lift their head far above the surface to make sure they get a sufficient breath. Unfortunately, this position severely Head over-rotated distorts the body position and causes CH3_SP10_G3 excess resistance.

Effective breathing position

Neutral head position not too far above surface.

o Blow out Competitive swimmers typically exhale continuously when the face is submerged. This prevents water from going up the nose and also prepares the swimmer to inhale when the mouth is next above the surface. A swimmer will exhale forcefully (through the nose and mouth) just before positioning the head to inhale, if necessary, in order to maximize the inhalation.

Ineffective breathing position

If the head is raised too far above the surface on the breathing cycle, the body position is badly distorted, causing unwanted resistance.

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What proportion of training should be focused on starts, turns, and finishes? When the subject of starts, turns, and finishes comes up, it’s often in reference to gaining a fraction of a second advantage, or losing a race to a competitor who touched the wall a split second sooner. Swimmers do get “touched out” in this way, but generally it is swimming speed that determines the outcome of a race. However, the combination of the start, the turns, and the finish can easily add up to a full second or more of benefit or deficit. It’s important to realize that starts and turns are very different activities to swimming itself. The push-off from the wall or starting block is similar to a jumping motion, a land-based activity that most humans perform many times. Training for starts and turns should not just include repetitions of starts and turns, but also land and water exercises designed to target the jumping motion. While the push-off motion is similar to jumping, the movements before and after the jump are unique in both starting and turning. Finishes are a swimming activity, but also require specific planning skills to get to the wall without a decrease in speed and without taking an unnecessary stroke. The underwater phase of a start or a turn is of particular importance. Competition rules allow swimmers to remain CH3_SP11_G1_A submerged to the 15 m mark. Some swimmers take full advantage of this rule and benefit because they can dolphin

How important are my starts, turns, and finishes? kick very fast. Mastering this skill can take years—swimmers must practice consistency by counting underwater dolphin kicks on each start and turn. Training sessions should also include repetitions of both the start and turn underwater motions that are timed and evaluated by a coach. The evaluation can determine if increasing the number of kicks is appropriate. Another factor to consider is the impact of starts and turns on different events (that is, sprints and distance events) and in different pools (long course and short course). For example, the start and the turn push-off can total as much as 30 m, which is about 60% of a 50 m sprint race. Many swimmers can swim faster than they can kick underwater so realistically, the percentage will be smaller (more like 35%). However, this is a still a substantial proportion of a sprint event and gives an indication of the proportion of training that might be allocated to these activities.

d Start strong, finish strong It requires a substantial number of practice repetitions to achieve a backstroke start entry that minimizes resistance (A). Unfortunately, backstroke starts are probably the least-practiced start, turn, or finish skill. Swimmers also need to practice the backstroke finish so they don’t lose time gliding into the wall (B). This activity is difficult to practice in many team training sessions when teammates may be standing in front of the wall, awaiting their turn to swim.

Backstroke start and finish

A

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B

Pool Training

CH3_SP11_G1_B

CH3_SP11_G2_BandC

CH3_SP11_G2_A

Optimum start

g Start of least resistance Swimming starts require practice to master a level take-off from the starting blocks to maximize distance, with an entry through a small “hole” to minimize resistance.

CH3_SP11_G5 d a Taking turns

During training and warm-ups, circle swimming is standard practice for competitive swim teams to maximize pool use. Circle swimming involves three or more swimmers in each lane, swimming from end to end in a circular pattern. However, sloppy turn habits often develop when swimmers have to be more concerned with avoiding collisions than with honing their skills. Swimmers often rotate their bodies at the wall so they can better view oncoming traffic (A). When swimmers have the luxury of their own lane, they can work to perfect their alignment (B). Swimmers need to practice the same push-off in training sessions that they use in competition. The angle of the push-off and the number of kicks underwater are key factors to track during training. Coaches can observe the distance from the wall at which a swimmer surfaces as well as the swimming speed.

Turning practice Rotating the body at the wall does not provide the optimum position to push off.

A

CH3_SP11_G3

With her back facing the pool floor and her feet aligned vertically, the swimmer can achieve the strongest push-off at the turn and stay beneath the turbulence.

B

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The first rule of dryland training is simple: do no harm. Always remember that dryland training is supplementary to our work in the pool. No matter what dryland training approach is employed, it is there to support swimming. For a swimming culture that has long followed a “more is better” approach in dryland training, the concept of restraint can be unsettling, yet essential. Safety and performance are not in opposition but rather complement each other. Another critical piece for any dryland program is to recognize that more “conditioning” is not needed for swimmers. When we say “conditioning,” we are referring to high intensity workouts that elevate the heart rate for extended durations. Better to keep the repetitions low and the recovery periods long to avoid overloading swimmers on top of their ample conditioning work in the pool. Many tools will work, but the points covered in this chapter should guide any dryland program.

chapter four

dryland training Allan Phillips

Does dryland strength training directly improve performance in the water? Strength training for swimmers is one of the broadest and most contentious issues in the sport. Not only is the question of its effectiveness widely unsettled, swimmers are hardly a homogenous group—age, distance, event, injury, technique, length of training program and experience are among the many variables that can significantly impact outcomes of any training intervention. For example, the strength training goals, and expected adaptations, will be different for a distance swimmer compared to a sprinter. Swimmers have concerns about negative effects from strength training such as fatigue, excess bulk, and loss of aerobic performance—many worry that strength training may damage the vital oxygen delivery network to muscles and organs provided by capillary development. Of these concerns, fatigue appears to be the most valid, as overtraining is certainly possible if swimmers’ workloads are not properly managed. But research has shown that a strength training program should not increase body mass, nor should it negatively impact aerobic benchmarks such as VO2 max and capillarization, as long as the swimmer maintains an aerobic training baseline alongside.1 Because swimming takes place in an unstable medium, it is advisable to incorporate unstable surface training into a dryland program. This training should not be the centerpiece, but can help bridge the gap between the land and the water. One effective modality is suspension training, which is most popular commercially through the TRX training system. In particular, exercises such as rowing and other posterior shoulder exercises help counterbalance the repetitive postures and movements in swimming and help train the core in a manner similar to the way it is trained in the water. According to existing research, the type of strength training most likely to improve swimming involves a small number of repetitions (reps) at high intensity, with longer rest periods. 98

Dryland Training

Will training on land help me to swim faster? General guidelines for improving endurance performance propose 5–8 reps per set of at least two exercises, for 3–5 sets per workout, 2–4 times per week over a 6–16 week program. It’s suggested that this type of training boosts performance by improving neuromuscular activation and musculotendinous stiffness.2 Excess stiffness is not always beneficial for swimmers but can be in certain instances. The results seem positive for low-repetition, high-intensity lifting. There is also evidence to suggest that the converse— high-repetition, low-intensity training—may not be beneficial, despite its popularity in swimming culture. A training intervention using three exercises of 8–12 reps found no significant improvements in 50 yd and 400 yd (46 m and 366 m) swimming performance,3 while swimmers who included 6 sets of 50 s work/10 s rest on the ergometer in their regular circuit training performed no better than swimmers who underwent no supplemental aerobic training. Since swimmers already perform high volumes of endurance training in the pool, the potential for overtraining by incorporating aerobic sessions in dryland programs is of concern. With any dryland approach, it is critical that swimmers “earn their way” to the next level of difficulty. Swimmers should master the basics before advancing through more difficult progressions en route to higher levels of dryland performance.

How strength training affects endurance performance No increase in body mass

Improvements in exercise economy

No reduced capillarization

Improvements in lactate threshold

No negative effect on VO2 max

Improvements in maximal speed

Reduced fatigue

Improvements in anaerobic capacity

Load

Repetitions per set

Sets

Rest between sets (minutes)

≥85%

≤6

2–6

2–5

Power for a single-effort event

80–90%

1–2

3–5

2–5

Power for a multiple-effort event

75–85%

3–5

3–5

12–53

Hypertrophy (building muscle mass)

67–85%

6–12

3–6

0.5–1.5

≤67%

≥12

2–3

≤0.5

Strength

Muscular endurance

o Workload management To set an appropriate dryland training program, it helps to understand the workloads needed to elicit positive adaptations in strength and power, depending on the training goal. Strength training for swimming optimally should remain in the ‘strength’ and ‘power’ ranges shown here—that is, low repetition and high intensity. Higher repetition, lower intensity training, which promotes hypertrophy and muscular endurance, has not been shown to elicit benefits for swimmers, and may lead to overtraining. The National Strength and Conditioning Association (NSCA) offers more detailed guidance on repetition and intensity ranges.

a Sprint strength

Strength training has the greatest potential to improve sprint performance. In a 12-week experiment, swimmers in a twice weekly strength training group underwent explosive dryland training, following a regimen of three sets of 6 reps/set, at 80–90% of 1RM, for each of six different exercises. This group improved their speeds by 2.8% over a 55 yd (50 m) sprint, compared to 0.9% improvement in the control group that was involved in an aerobic cycling program, and 2.3% in a group that underwent resistance training in the water using bands. All groups continued regular swim training throughout in addition to any interventions.5

d Less is more

In swimming, minimal dryland strength training is needed to gain benefits, possibly because many swimmers are relatively untrained on land, compared to other athletes. Improvements have been noted for sprint swimmers using only one exercise, following a regimen of three sets of 3 reps/set at 90% of onerepetition maximum (90% of 1RM), two sets of 2 reps/set at 95% of 1RM, 1 rep at 100% of 1RM and 1 rep attempted at 100% of 1RM + 2 lb (1 kg). In only four weeks, training four times per week, swimmers averaged a 7.3% increase in freestyle velocity over 55 yd (50 m).4

Fast improvement 0.3 A B

Percentage improvement in time over 55 yd (50 m) (%)

(percentage of 1RM)

Training goal

0.2

0.1 C

0.0

2.8 % improvement A

Dryland strength training group

2.3% improvement B

0.9% improvement C

In-pool resistance Control group training group

Sprint performance

3

et at reps/s

f 1RM

90% o

2 re

RM

% of 1

at 95 ps/set

% at 100 1 rep of 1RM

100% ted at ) p m e t t g a 1 rep + 2 lb (1 k of 1RM

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Could dryland training impair neural connections and impede swimming training? Many dryland programs use excessive volume and muscular endurance training. Contrary to traditional thinking, swimmers receive ample cardiovascular conditioning in the water and should focus land training on domains such as strength, power, and mobility rather than stamina and endurance. Even at the beginner’s level, training can be time intensive. Swimmers under 10 years old often spend more than five hours per week in pool training. At higher levels, training is a nearly full-time occupation, involving upward of 30 hours per week of active pool training. Compared to other sports, swimming performs a conditioning workload rivaled only by elite cycling, Nordic skiing, and rowing. Based on this alone, swimmers should consider reducing, or even eliminating, cardiovascular conditioning activities in dryland training.

Mixed training for maximal power Level of line at plateau shows peak force (strength)

Does dryland training help or harm my swimming?

Swimmers use many forms of dryland training, both in the weight room and on the pool deck, using various equipment and bodyweight-only exercises. One common approach is to perform diverse exercises in rapid succession, known as circuit training. Training for peak performance should focus on the least developed factor contributing to maximal power generation. This results in the greatest neuromuscular adaptation, and therefore in the most significant improvements in performance.1 Swimmers are generally deficient in factors such as neural activation and rate of force development, which require optimal functioning of the nervous system to maximize recruitment of primary motor units (motor nerve cells and the skeletal muscle fibers they innervate). Neither quality is maximally developed through high-volume circuit training, in which strength training takes place concurrent with cardiovascular demands, as the nervous system is unable to “focus” on force development in specific muscles. Fortunately, when training properly—taking plenty of rests between sets of specific, targeted exercises—swimmers may experience gains in these domains within 4–6 weeks.

Force (newtons)

Whether dryland training actually impairs swimming is difficult to measure. But based on the science, we know that if you do not train in the recommended ranges for adaptation, strength and power gains will be limited, and your dryland program will only be making you tired and sore.

g In the mix A mixed training program maximizes rate of force Initial gradient of line shows rate of force development, power = or power

force time

Time (milliseconds)

100

Before training

After heavy resistance training only

After ballistic training only

After mixed training

Dryland Training

development and power. Ballistic or explosive training improves rate of force development, by recruiting more motor units than in ramped contractions, but cannot alone increase overall peak force (strength) significantly. Heavy resistance training, on the other hand, improves peak force, but does not result in a large increase in rate of force development without explosive training too. A blend of explosive and heavy resistance training is therefore the optimum for enhancing power production.

NEED TO KNOW Rate of force development (RFD) Rate of force development is a measure of an athlete’s explosive strength, which depends on the speed at which muscle fibers can contract. Athletes with higher rates of force development perform better in various physical performance tests. In trained athletes, only anaerobic GRAPHIC CH4_SP1_01_A_Squat systemINFOtraining, such as resistance and ballistic exercises, have been shown to improve RFD.

d Power up High power output underlies effective performance in many sports, including swimming. Power is defined as the amount of work done per unit of time. So, while strength determines the maximum force an athlete can apply to a given load, power is proportional to the speed at which the force is applied. In swimming, we can interpret this as the rate at which force is exerted by the muscles to propel the body through the water. Dryland training programs can be designed to improve maximal power output by focusing on particular types of exercises, such as ballistic, plyometric, and weightlifting exercises1, as outlined here. The consequent benefits of enhanced power production transfer well to performance in the pool.

INFO GRAPHIC CH4_SP1_01_E Couple of line weights INFO GRAPHIC CH4_SP1_01_B

Power production

Strength Since power involves both strength and speed, increasing strength is key to improving power output. Heavy resistance training with loads ranging from 50% to 90% of 1RM can significantly increase peak force.1

Variation It is thought that the greatest long-term improvement in an athlete’s maximal power output can be achieved by integrating a variety of different power training techniques within the training program, including both heavy resistance and explosive exercises.

Ballistic Ballistic training—which includes exercises such as jump squats, bench throws, and push presses—is used to develop explosiveness and power. The athlete accelerates and then releases the load, rather than slowly decelerating it as in other forms of weight training. Ballistic movements require coordination of the central nervous system to recruit fast-twitch muscle fibers, which are directly responsible for growth and strength, resulting in enhanced rate of force development. Loads of up to 50% of 1RM are found to be the most effective for improving maximal power in complex movements.1

“Window of adaptation” Various neuromuscular factors contribute to maximal power production, including muscle mass and strength. Identifying the individual’s least developed factor, and designing a training program to focus on appropriate neuromuscular adaptations, presents the greatest potential for improvement in maximal power output and, therefore, inINFOperformance for that GRAPHIC CH4_SP1_01_C individual. In swimmers, rate of force development (power) and neural activation are often the least developed factors.

Plyometric In plyometrics, or “jump training,” the muscles exert maximum force in short time intervals, in order to build power. For example, plyometric drills such as specialized repeated jumping involve muscles moving from extension to contraction in a rapid or explosive manner. In swim training, plyometric exercises should involve stretch rates that are similar to those encountered in the pool, and involve little or no external resistance.

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What type of core training is beneficial for swimmers?

Will sit-ups and crunches improve my swimming?

The potential benefit of core training for swimming is a hotly debated topic and one on which there may never be a consensus. Although core training is a staple in many dryland programs, the formal literature supporting its effectiveness is sparse. There are several reasons for this void, but most significant is that “core training” is such a broad term with many working definitions. Sit-ups, medicine ball training, unstable surface balancing and traditional weightlifting are among the many tactics commonly associated with core training. Despite the breadth of options available, it is possible to organize a set of universal principles to guide training choices in this area. It is perhaps easiest to begin with what not to do. Sit-ups, crunches, and their various iterations are the most popular class of core exercises in the swimming world—yet they should probably be the first group of exercises to omit from a dryland training program. Recent evidence has shown that repeated spinal flexion (bending forward, as in a sit-up or crunch movement) increases the risk of low back damage, and also tends to encourage the most common postural deviations in the swimming population, such as rounded upper back and forward shoulders. This is not to suggest that spinal flexion must always be avoided. In fact, the ability to bend forward with power is essential for optimal turns. But multiple turns do not occur in rapid succession, so training the core to carry out sets of repeated sit-ups and crunches is unlikely to bring directly transferrable benefits. A better approach, if you choose to include forward bending in your core workouts, is to train this movement in lower volume, using fewer repetitions and longer rest periods than in traditional sit-up and crunch training. A foundational principle of core training for swimmers is that it should include a specific component for swimming function. For example, a recent study compared the effects of a variety 102

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of core training exercises on the performance of swimmers completing a sprint test.1 Among the exercises tested, the prone bridge endurance test (more commonly known as the “plank”) and straight-arm pull-down exercise resulted in moderate increases in strength and were correlated with a 2% performance improvement in the swim test. On the other hand, isometric strength tests and exercises performed on unstable surfaces had less transferability to swimming performance.

Muscles of the core

Latissimus dorsi

Erector spinae

Multifidus (deep)

Gluteus maximus Gluteus minimus (behind gluteus maximus)

External oblique

Rectus abdominis

Gluteus medius (mostly behind gluteus maximus)

Internal oblique (deep) Transverse abdominis (deep)

Developing core strength

gd Plane and simple There are several reasons why a degree of swim specificity may be valuable for dryland core training. In the plank and straight-arm pull-down exercise, which have been shown to be beneficial for swimmers,1 the core is positioned to transfer load along the same angles and in the same planes as demanded in the pool. In the endurance plank, the body must maintain a streamlined position for an extended period of time, much as in most swimming events. Likewise, in the straight-arm pull-down the body must maintain stability in the sagittal plane as the upper limbs are generating force, which progresses high to low as with the pull in the swim strokes. These exercises are only two of the many available options for developing core strength—the key components of core stabilization and directional pull similar to that used in swim strokes can be used as criteria to select other exercises particularly suited to dryland swim training.

Prone bridge endurance test (plank)

Body planes Sagittal plane

Straight-arm pull-down exercise

g Getting to the core

The core comprises far more than just the “abs”—it includes deep muscles such as the diaphragm, pelvic floor muscles, transverse abdominis, multifidus, and internal obliques, as well as the more superficial external obliques, rectus abdominis, latissimus dorsi, erector spinae, and gluteus muscles. Developing core strength protects the spine, reduces back pain, improves balance, stability and posture, and—when trained appropriately— can also enhance swim-specific movement patterns.

Transverse plane Frontal (coronal) plane

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equipment: stretch cords In this age of complex training equipment, one of the simplest pieces is also one of the most effective and versatile: the stretch cord. Stretch cords share many characteristics with the swim bench, but have certain advantages over it. One obvious advantage is their portability—stretch cords are light and flexible and can be used almost anywhere. Seen on many pool decks, in gyms, and at rehabilitation facilities, stretch cords have historically been used in ways driven largely by tradition rather than science—nevertheless, we can infer the mechanisms by which they may work. To get the best value from stretch cords in dryland training for swimmers, it is first important to determine where in the

d Stretching strength A key for any shoulder program is to train the shoulders and upper back muscles in multiple planes of motion. Doing so will help address any imbalances in the shoulders that develop through repetitive use in the water. When programming for rehabilitation or a swimmer with an injury history, the balance of the program should be modified to address that swimmer’s weakness. As such, some planes of movement will receive extra emphasis while others will be deemphasized or excluded altogether. This graphic shows abduction and adduction exercises in the transverse plane.

different stroke phases added resistance may be helpful. In each of the four strokes, there are points at which stretch cords may be most effectively applied—for example, in freestyle these are during the early catch with a vertical forearm, the high elbow pull, and the finish at the back. When using a stretch cord, it is key to ensure that posture is optimal—even if your arm technique is good, you will defeat the purpose of the exercise if you perform it with poor posture. The most common flaw is to have a rounded back during stroke simulation. To execute the early vertical forearm and high elbow, visualize pointing your fingers at the ground while maintaining elbow position and ensuring that it does not lose height. There are many equipment options for dryland resistance training, and none is universally superior to the others. For example, barbell training can be useful, but is hardly the right method for improving technique; stretch cords, on the other hand, are versatile but are not sufficient for full-body power development. Overall, it’s crucial to deploy a range of equipment in a manner that best leverages each piece’s inherent qualities, to work toward the training adaptations you are seeking.

Shoulder strength

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Types of stretch cord

ga Flexible Standard stretch cords have a handle at each end, but there are products available with paddles instead, to allow a swimmer to more accurately replicate the upper limb positions and actions of swimming.

Standard stretch cords

Stretch cords with paddles

Strength development for young swimmers

gd Exercise anywhere Stretch cords can be used for strength development. Although the loads may be insufficient to challenge adolescent and older swimmers, stretch cords are a valuable addition to dryland training for young age group swimmers to teach basic lifting mechanics as an introduction to strength training. Rows are one of the simplest exercises to implement.

Stretch cords can be looped around any convenient pole or other firm attachment, to perform resistance exercises such as rows.

d Dry run

A range of cords are available, providing different levels of resistance—the resistance can also be increased by stretching the cord further.

Dryland stroke rehearsal is an important use for stretch cords. It’s possible to replicate several key movements on land that many struggle with in the water. The early vertical forearm paired with a high elbow catch is one movement that is much easier to establish on land with the assistance of stretch cords. The finish of the freestyle stroke is another phase of the stroke cycle that can be rehearsed on land, with opportunities for feedback that are difficult to create in the water.

Stroke rehearsal

Exercise to practice early vertical forearm with a high elbow catch and finish, in freestyle.

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Can dryland plyometrics enhance performance in the water? Plyometric training involves rapid, “explosive” actions, in which the muscles contract with maximum force in a short time, in order to build power. For example, plyometrics often include jumping, sprinting, and agility drills, and are commonly used in dryland training programs for swimmers. While we aren’t certain if these drills directly aid swimming, there is reason to believe that such exercises may enhance starts and turns. For example, a study of trained adolescent swimmers found that, while plyometric training did not change the take-off and airborne properties of the start, it was associated with improvements in overall time to the 6 yd (5.5 m) mark in the pool.1 However, a different study, comparing swimmers who trained using plyometrics and swimmers who trained solely in the water, found no difference in turn performance between the two groups.2 Though conventional wisdom might suggest that plyometrics would have limited direct benefit for swimmers, because the trained movements it involves—such as jumping and bounding—are not specifically related to swimming

Will exercises such as jumping and agility training help me swim better? movements, research has shown that plyometric training does improve glide speed and stroke velocity.3 Regardless of any direct benefits for swimming, plyometric training has been shown to increase general measures of athletic ability (such as jumping, sprinting, endurance, and agility) and to reduce injury risk, which may help improve durability for other forms of dryland training. Thus, plyometrics may have an indirect effect on swimming performance, not felt in the short term. Gains in a plyometric program should be noticeable within an eight-week training protocol of 2–3 sessions per week. Due to the demanding nature of plyometrics, especially for athletes not fully conditioned to repeated ground impacts, adequate recovery is essential between repetitions, with a minimum of a 1:10 work-to-rest ratio. This augmented rest interval allows the body to increase neural drive to working muscles—which may

The stretch-shortening cycle A Eccentric phase As the athlete sinks into a squat, the agonist muscle groups in the calf and thigh are stretched. Elastic energy is stored, and muscle spindles are stimulated, which triggers impulses in sensory neurons as part of the stretch reflex.

a The reflex

The stretch-shortening cycle is the basis of plyometric exercise. It harnesses both the elastic energy stored during the rapid musculo-tendinous stretch of eccentric muscle action, and the increased neural drive resulting from the stretch reflex, to optimize the force produced during subsequent concentric muscle action. By combining both mechanical and neurophysiological mechanisms in this way, plyometric exercises such as repeated squat jumps maximize muscle recruitment over a minimal amount of time. Plyometric training has been shown to elicit a number of physiological adaptations, including increased muscle size and strength, increased bone density, increased tendon stiffness and reduction in energy dissipation allowing more efficient muscle action, and—perhaps most significantly—increased neural drive to agonist muscles.

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A

C B

B Amortization phase This is the rapid transition from eccentric to concentric phases, during which impulses in sensory neurons pass to motor neurons via synapses in the spinal cord. C Concentric phase This phase comprises the entire push-off time, until the athlete’s foot leaves the surface. Motor neurons stimulate agonist muscle fibers to contract rapidly (neurophysiological), and elastic energy is simultaneously released (mechanical).

d Jump to it The effects on front crawl performance of plyometric training, in addition to the usual swim program, were studied in a group of 14-year-olds.3 The swimmers were assigned either to a control group, or to a test group. Both groups underwent 5.5 hours per week of swim training during a six-week block. In addition, the test group also underwent plyometrics before swimming training two times per week, involving squat jumps and counter movement jumps as shown here. The test group showed a small but significant improvement in front crawl speed over 50 m and 400 m, compared to the control group, and there was also a significant correlation between improvement in jump performance and increased swim speed over 50 m, suggesting that plyometric training may have a positive effect on The CMJ involves short-duration pre-loading of the agonist muscles swimmers’ performance, particularly and tendons followed by immediate involving diving and turning maneuvers. contraction. It provides a greater degree of plyometric movement compared to the squat jump.

be responsible for the in-water improvements found in glide and stroke velocity3 despite the fact that the exercise movements are not specific to swimming. It is important to note that many studies on the effects of plyometric training in swimmers include control groups who performed no alternative dryland training. A more realistic inquiry would compare plyometrics to other forms of dryland training, as well as studying interactions between different types of training programs. Additionally, much of the formal research on the topic is restricted to narrow age groups of adolescents with a varying range of swim experience.

Squat jump

In a CMJ (counter movement jump) the athlete starts in a standing straddle position (A), squats down rapidly (B) and then immediately jumps up from that position (C).

The squat jump (SJ) is performed from a static squatting position

Counter movement jump

A

B

Start performance Change in time to 6 yd (5.5 m): 0.38 s

Change in take-off velocity (m s–1): 0.12 m s–1

–0.07 m s–1

0.19 m s–1

C

d Quick off the mark An eight-week study looking at the effects of additional plyometric training on start performance1 in adolescent swimmers revealed a significantly greater improvement in time to the 6 yd (5.5 m) mark in the “plyometric” group compared to the control group. It also showed a significant improvement in velocity of take-off from the starting block in the group who experienced plyometric exercises in addition to their normal swim training. Since start performance is so critical to swimming success, this evidence suggests that inclusion of plyometrics in the training programs of adolescent swimmers should be beneficial. 0.21 s

Standard swim training plus plyometrics (test group) Standard swim training only (control group)

0.59 s

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Does resistance training at a young age impair a child’s growth? Resistance training describes any exercise in which resistance is applied to the body’s work. This can be in the form of external weights, but resistance can also be applied using nothing more than one’s own bodyweight—push ups and pull ups are examples of bodyweight resistance exercises. Nearly everyone agrees that the latter form of resistance training is not only safe, it is essential for optimal youth development, for athletes and non-athletes alike. Kids will undergo some forms of resistance training as they simply play various everyday games. Bodyweight training is nearly universal among youth swim programs, and rightfully so. Coaches should introduce swimmers to some form of resistance training at a young age so that their first exposure won’t be at high school or college, where the dryland program is likely to be more intense. Although the evidence connecting dryland training directly to swimming performance remains uncertain, in the younger age groups performance gains are not the priority in any case— injury prevention and establishing a base for the future are most important. Coaches should not feel that their young swimmers are at a disadvantage if they only have access to bodyweight. The main discussion involves whether young kids should train with external weights. A common belief is that training with weights will stunt a child’s growth, but this is unsupported in the scientific literature.1,2 While improper training can cause musculoskeletal injuries, there is no evidence that a properly designed weight-training regimen would either cause injuries or delay optimal growth. In fact, the overall evidence suggests that a properly designed resistance training program offers numerous benefits for young athletes, including improved body composition, more robust self-esteem, greater opportunities for social interaction, strength development, power, athleticism, and injury prevention. Additionally, there is some evidence that the inclusion of resistance training might have an effect on swim performance, though this remains subject to ongoing debate.3 108

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How young can kids start training with weights and other forms of resistance? Resistance test Power training group Standard training group

135 N

120 N 100 N 90 N

1000 N

1000 N

1000 N

Pre test

1,000N

1000 N Post test

1,000N

Pre test

1,000N

1,000N

Post test

Age 5–12 resistance training Power kicks and leg raises Running and skipping

Climbing Wall sits Start basic strength training by introducing young children to many different sports and fun activities— emphasis on just one can lead to burnout, boredom, and repetitive motion injuries. Teach fundamental skills for agility, strength, and endurance, as well as specific sports skills.

Push ups and planks

Swimming and pool play

Bridges

Crunches and medicine ball throws

gd When to begin It is almost impossible to assign a milestone date at which kids should start resistance training but some guidelines are available. At a very early age, children are learning fundamental motor skills and building the neuromuscular pathways needed for coordination. The simplest exercises are appropriate, and most important is making movement and exercise a positive and social experience. Five is generally considered the earliest age at which kids should begin structured resistance training, which should comprise bodyweight-only exercises such as push ups, monkey bars, and any other playful activities providing resistance to movement. Formal weight room exercises such as bench pressing should be saved for later years. It is vital to take into account the individual’s stage of development—two kids of the same age might be at entirely different stages of physical and mental growth. One twelve-year-old may be ready for formal weight training while another may be safer remaining in a bodyweight training program. If in doubt, it is best to err on the side of caution and wait longer—many swimmers have enjoyed success without picking up a weight through their adolescent years.

Age 13–20 resistance training Triceps kickbacks

Bench presses

Teens can get into more advanced strength and conditioning training but always focus on socializing, building self-esteem, and developing a regular and consistent workout routine, promoting an active and healthy lifestyle into adulthood.

g Taking the strain

Although the evidence associating resistance training with enhanced swimming performance is not great, in one study comparing an experimental group of young swimmers whose training included a power program with an equivalent group who underwent swim training only, a significant improvement of tethered swimming force was found for the experimental group over a six-week period, whereas the increase was not statistically significant from pre-test to post-test conditions in the control group.3 (The tethered swimming force was determined by connecting the swimmers to a 1000 N load with four strain gauges attached using commercial elastic cord. Strength was evaluated in tests over 10 seconds.)

Barbell squats Lunge and press

109

SCIENCE

IN ACTION

measuring dryland performance

We are currently in an era of measurement in sports science. Nearly every form of biomechanical and physiological output can be measured. Unfortunately, swimming lags behind other sports in this respect simply because making measuring equipment waterproof incurs an additional layer of cost. However, land-based technologies are equally accessible to swimmers and non-swimmers alike—they can be divided into three categories according to what they measure: readiness, output, or technique. A swimmer’s readiness can be assessed by simple observation: is the swimmer showing signs of fatigue, rapid weight loss, or other abnormal indicators? Dryland training offers a coach the closest perspective to conduct such observations. Another simple readiness measurement technology is a questionnaire, asking swimmers questions in either written or spoken form. More in-depth assessments using blood testing can be extremely useful to monitor various biomarkers. Traditionally, the primary output measure of dryland performance has simply been whatever is the main goal of the exercise—the weight lifted, or the height jumped, for example. Among the new output measurement technologies now available are force plates, electromyography (see pages 174–175), and bar speed trackers, which allow coaches to look deeper into the performance of an exercise. Force plates are commonly used in high-impact activities but can also be used during stationary lifts to measure how the athlete interacts with the ground. Swimmers often feel out of place on land, and force plate data can be used as a teaching aid to accelerate their proficiency. Electromyography reveals which muscles are firing and to what degree, while bar speed trackers measure how fast the bar is moving during barbell lifts. The most common way to observe and measure dryland technique is using video cameras, which have become dramatically more portable in recent years. For many athletes, video footage is a reality check on the soundness of their lifting technique, especially for swimmers who may be inexperienced with dryland lifting. Threedimensional motion capture can break down technique by body segment and provide even more detailed feedback.

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Dryland Training

a Observing dryland performance French swimmer Laure Manaudou lifts weights during a training session in Val-d’Isère, French Alps. Nothing replaces hard work, but harnessing technology can improve our return on investment.

Does visualization help develop neural networks?

Can visualizing my performance help me swim better?

One of the new horizons in swim performance is the use of mental training outside the pool. Although many perceive mental training as building toughness to persist through difficult practice and race schedules, it certainly transcends that limited scope. Mental training outside the pool is traditionally not considered part of dryland training but can have profound effects to complement physical training, both in and out of the pool.1,2 For you to perform optimally, your brain must have an idea of your intention. Because swimming training is so embedded in routine, we often overlook our ability to control our thoughts. Conscious thought and visualization of your intended actions can be vital in many swimming contexts—for example, visualizing stroke mechanics and strategy in preparation for a race. Mental imagery also helps to sustain technique during times of fatigue by creating a more robust mental imprint upon which the swimmer can rely when physical duress increases.3 In addition, visualization practice can help maintain neural networks during times of physical idleness—during rehabilitation following anterior cruciate ligament reconstruction, for example. Even if the body loses function mechanically, the nervous system remains primed for a return to the pool so the swimmer loses minimal progress upon resuming a normal training load. Neurological changes resulting from mental training are tangible—research has shown an increase in neurotransmitter release after visualization practice by competitive swimmers.4 The practical implications are profound. Not only can you potentially get more out of your practice, but also—some suggest—the body could be spared overtraining by replacing physical training with mental training. That is, visualization may allow swimmers to access different training adaptations without wearing the body down. There are still questions about whether visualization training could cause overtraining of the nervous system, but thus far no research has explored that possibility. Overall, the best results come from combining mental imagery 112

Dryland Training

and physical practice. Mental practice cannot teach you to do something for which you have never physically trained—but it can help you achieve a greater return on investment for the time you spend in the water, improving the quality of practice.

Effect of visualization training Time (s) to swim 1000 yd 631.5

630.9

729.4

685.8

756.5

747.2

781.0

767.0

Without visualization After using visualization techniques Participant 1

Participant 2

Participant 3

Participant 4

Visualization practice

For optimal performance, swimmers can use specific imagery to decrease or increase arousal, or to refocus when faced with distractions during practice or competition. Imagery can be used as an additional form of practice to help swimmers master skills and techniques. For example, swimmers may visualize themselves executing perfect stroke mechanics prior to a pool training session.

To prepare for competition, swimmers can familiarize themselves with the competitive environment and rehearse their performance through visualization. Experts recommend involving as much of the sensory panorama as possible—not only the race, but also the sounds of the pool area, the smell of chlorine, and so on. Using imagery to experience success and the achievement of goals helps to enhance swimmers’ self-confidence. It also provides the motivation to maintain persistence and intensity level during training and competition.

g Seeing is believing

Imagery techniques do seem to have a measurable influence on swimmers’ performance. In one study, performance times on a 1000 yd practice set were collected for four swimmers over a 15-week period during pre-season training.2 After week 4, a visualization training intervention took place over three weeks. The results showed that three of the four participants significantly improved their times on the 1000 yd practice set after being introduced to the imagery techniques.

o Just imagine

Visualization is important for swimmers not only to see and feel success, but to rehearse specific patterns of neural activity, to enhance subsequent physical practice. There is a lot of “downtime” between events at swim meets, so having a mental plan to maintain engagement is vital, especially for swimmers who struggle bringing their best performances from practice to competition. Swimmers can also use imagery to develop strategies to overcome “unexpected” situations—if they have rehearsed it in their minds, they will know how to deal with it.

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What type of flexibility training best enhances swimming-specific range of motion?

Which stretches will improve my swimming?

Flexibility training must be purposeful, appropriate for the setting, and individually tailored. Swimmers practice flexibility training to achieve ranges of motion necessary to execute swim-specific movements. For example, joint mobility exercises targeted at the hips, shoulders, thoracic spine, and ankles may be prioritized, as these are the areas in which flexibility is most important in swimming. A wide range of practices can be included within flexibility training—stretching is just one of several methods by which flexibility can be addressed.

For example, static stretching is not advised in pre-event warmups as it has been shown to decrease power output. After swimming, though, while the body is still warm, static stretching can help improve flexibility with less likelihood of injury. Static flexibility exercises also help the body cool down after a workout—each stretch should be held for 20–60 s, as going any longer yields no further benefits. Though not specifically stretching, myofascial release using a foam roller helps improve flexibility without any decrease in power generation.1

Dynamic stretching includes exercises such as arm circles and leg swings, in which muscles and joints are not held in one position, but instead moved through a full range in a controlled action. Pre-event warm-ups usually involve dynamic stretching, which not only helps to elevate core body temperature but also rehearses key movements, such as ensuring the shoulders can safely execute the range of motion required by stroke mechanics. Static stretching involves taking a muscle or joint near its maximum range and holding for a sustained length of time. It can improve specific ranges of motion but is not always appropriate.

Although flexibility training is typically advised, in some circumstances injury history and personal characteristics supersede the general considerations. For example, swimmers with hypermobility can move a joint beyond its normal range of motion—knees and elbows that bend backward are common examples. Because hypermobile swimmers often present with a history of shoulder instability, additional stretching can make them more unstable, so they should focus on stability exercises, and possibly reducing flexibility, as a relationship has been shown between joint laxity and shoulder pain in swimmers.2

Dynamic stretching, before training Shoulder internal rotation

Compound dynamic stretch—shoulder extension with hip, knee and ankle flexion

Static stretching, after training

g Stretching a point

Generally, guidelines suggest using dynamic stretching before a training session or competition event, and focusing on static flexibility after training (if at all). For swimmers, emphasis should be placed on improving flexibility in the shoulders, upper spine, hips, and ankles. Swimmers’ individual qualities and context must always be taken into consideration, however.

Leg stretch

114

Dryland Training

Shoulder and upper spine stretch

Shoulder internal rotation strength 30

Force exerted, as percentage of body weight (%)

29 28 27 26 25 24 23 22 21 20

Flexibility trained group

Control group

Shoulder extension strength

Force exerted, as percentage of body weight (%)

30

o Flexibility in strength

Many studies have been conducted assessing the effect of stretching on swimming performance. One recent study relevant to the highly competitive population was conducted to assess the effectiveness of a six-week strengthening and stretching program in improving shoulder strength in college swimmers.3 Although strengthening is different from stretching, there is reason to believe that strength improvements within

the rotator cuff can translate into flexibility improvement, hence the inclusion of both types of exercises in the study. Of the 44 swimmers who took part, the intervention group completed a program of strengthening and flexibility exercises using resistance tubing three times per week for six weeks. These swimmers showed small improvements in many areas, but shoulder extension and shoulder internal rotation strength were significantly increased.

29 28 27 26 25 24 23 22 21 20

Flexibility trained group

Control group

Before intervention After intervention

115

Does dryland stroke rehearsal on a swim bench improve motor learning in the water?

Should I use a swim bench to practice my stroke on land?

A swim bench is often touted as an effective way to supplement the training load in the pool and plays an integral role in many teams’ dryland preparation. For teams whose pool time is limited, swim bench training provides the closest equivalent to swimming, and it can also allow refinement of stroke mechanics not easily achievable in the water.

into a zone of diminishing marginal benefits. Although the cardiorespiratory demands of the swim bench are less than for actual swimming, the musculoskeletal demands are similar.1 Additionally, users should understand that the swim bench may allow muscle asymmetries to persist, without exercises specifically targeted to address those areas.2

For a beginner, a swim bench offers the opportunity of realtime feedback from the coach, which is nearly impossible during a team practice in the pool. Achieving optimal stroke mechanics can involve joint angles highly foreign to someone with little swim experience. When used properly, the swim bench can accelerate the learning process and make time in the water more effective. For more advanced swimmers, the greatest benefit of the swim bench is in tackling qualities that are more difficult to address in the water. The enhanced conditioning resulting from swim bench training may also allow swimmers to better maintain stroke mechanics under duress.

Furthermore, although the arm movements during bench training may look very similar to what swimmers perform in the water, stroke mechanics include a vast array of visually imperceptible microadjustments to manipulate the water for optimal balance and orientation. Additionally, although much of the focus is on arm mechanics with the swim bench, a bigger disparity between the pool and dryland conditions lies in the trunk and lower body. Unlike freestyle in the pool, during which the trunk rotates noticeably and the lower body participates actively in balance and propulsion, the trunk and lower body sustain isometric contractions against the belt when on the swim bench.

Balanced against these potential benefits is the risk of overtraining. Swimmers already train very large distances each week and adding swim bench dryland work could bring them

Pros and cons Swim bench training can offer significant benefits, but the potential downsides should also be considered. Benefits

Drawbacks

• Allows maximum communication with the coach

• Potential overtraining

• Isolates key parts of the stroke for refinement

• Trunk and leg muscles are supported, unlike in water

• Teaches mechanics to beginners without apprehension of the water

• Does not train microadjustments that occur in the water

• Increases training load

• Asymmetries persist, without other focused training

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Stroke practice High-elbow catch, as the arm enters the water at the start of the stroke

A

g On the bench

The swim bench is often used as an adjunct to pool training. Propulsion on the swim bench requires many of the same biomechanical actions required for effective freestyle and butterfly (the two strokes most commonly trained on swim benches): high elbow catch (A), maintained high elbow during the pull (B), and arm extension to finish the stroke (C).

Maintaining high elbow during the pull

Arm extension to finish the stroke

B

C

Eccentric phase

In the eccentric phase, during the later part of the stroke, muscle contractions work against the resistance in the bands

a Eccentric actions

For the advanced swimmer, because of the added force it requires to initiate the propulsive phase,3 the swim bench may be particularly valuable to focus on this part of the stroke, in freestyle and butterfly, though the middle and end phases can also be isolated for refinement. Additionally, swimmers can train the eccentric phase of the stroke, which is nearly impossible in the pool—after performing a pull, the eccentric phase can be trained by controlling the paddles as they tend to rise toward the front of the machine. Stroke tempo variation can also be practiced.

In the propulsive phase, muscles contract concentrically to pull the hands backward

117

Swimmers have two primary warm-up strategies available: in the water and on land. Coaches typically plan a pool warm-up before the main swimming set, but a significant portion of the whole warm-up session often occurs on land. One reason for this is that, at competitions, the warm-up pool may be chaotic and crowded, forcing swimmers to warm up elsewhere. Swimmers may also have long waits between the end of their allocated in-water warm-up period and their race—to stay warm and loose, the only choice is to use a dryland warm-up. Evidence shows that a wait of approximately 10–15 minutes between the end of the in-water warm-up and the start of the race will not affect performance, but waiting excessively (for 45 minutes or longer) may impair performance.1,2 Although research has not yet specifically looked at the impact on performance of a dryland warm-up during the wait, we can infer that it may help bridge that time gap. Ideally, the warm-up session should be as routine as possible, but in practice it may vary widely depending on circumstances. The optimal warm-up for competition may be different from the best format for a training session, when the warm-up can be open ended and gradually flow into the main swimming set if the coach desires. Some consider that warm-up swimming is often of poor quality, partially reinforcing bad habits. For this reason, coaches may forego part of the swim warm-up and instead transfer some warm-up exercises to land. One objective of the warm-up is simply to elevate core temperature, which is not specific to swim mechanics and can be accomplished on land, saving the in-water warm-up for stroke rehearsal. Another reason a dryland warm-up may be valuable for swimmers is that the start of a race occurs on land. It is critical, especially for sprint events, to achieve a powerful start, and the warm-up should address this need adequately. Post-activation potentiation can play a role here—this is the phenomenon by which prior muscular output improves subsequent performance. 118

Dryland Training

Will warming up before getting in the pool help me in the water? For example, performing countermovement jumps beforehand has been shown to improve swim start performance.3 Coaches must be sure to test such strategies in practice, however, before employing them in competition situations as excessively heavy loads may create soreness and impair performance. As with any warm-up format, it is critical to find the right balance of intensities for each individual.

Swim start improvement 1550 Swim start after swim-specific warm-up Swim start after dryland warm-up (performing countermovement jumps)

1518

1500

Peak vertical force (N)

Is a dynamic dryland warm-up necessary?

1462 Peak horizontal force (N)

1450 750

770

800

814

850

o Jump to it “Priming” the muscles using certain movements may improve subsequent performance, through what is known as post-activation potentiation. For example, one study showed a significant increase in both peak horizontal force and peak vertical force in a swim start after a warm-up involving countermovement jumps (see pages 106–107), compared to after a swim-specific warm up, as long as adequate recovery (of about 8 min) is allowed between the warm-up and the start.4

Dryland warm-up exercises

Core body warm up Light exercises to warm up the core body temperature e.g. jumping jacks, running in place, using a stationary bike

d All in the preparation Evidence has shown that there may be little difference between the benefits of a swim warm-up and a dryland warm-up, in terms of their effect upon subsequent sprint swim performance in college swimmers. A study compared the effects of an in-water warm-up, a dryland warm-up, and no warm-up at all.4 The swimmers’ subsequent times for 100 yd (91 m) freestyle were significantly better when they had warmed up than when they had not, but the slight variance between performances following swim warm-up and dryland warm-up was not significantly different. In recent years, some coaches have completely omitted in-water warm-ups for their swimmers and warm-up exclusively on land. Although the research in this area is still developing, there are indications that a dryland-only warm-up can be effective. Slight variations Average time (seconds) for 100 yd freestyle 60

60.5

61

Swim warm-up

Dryland warm-up

No warm-up

Motor control Motor control exercises e.g. practicing the catch and pull with light resistance bands

Dynamic flexibility stretches Dynamic flexibility stretches e.g. arm and leg swings, arm circles, running drills

Plyometric exercises e.g. explosive jumps and landings, medicine ball work

o Warming to the idea Objectives for the warm-up include elevating core body temperature, rehearsing movement patterns, enhancing mental readiness, and providing brief exposure to different energy systems to minimize the shock of intense training or racing. Dryland warm-up exercises might include some of the exercises shown above.

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Does increased sleep improve recovery? For decades, swimming culture has glorified sleep deprivation. The willingness to endure years of early morning practices has been a source of pride for swimmers who persist in the sport while others drop out due to the challenging lifestyle. Unfortunately, sleep deprivation has also been linked to poor recovery, injury, and illness. Though the science of sleep and its importance has become well established in recent years, changing cultural norms in the sport is a slower process. Most important is to educate coaches, swimmers, and parents, and allow them to make decisions based on the available science. Swimmers face many unique challenges with sleep, most notably the routine of very early morning practices. In an ideal world, practices would occur during the day, with opportunities for naps and refueling. Many college programs hold practices during daytime hours to alleviate concerns about the impact on sleep of early morning or late evening training, but this is rarely practical for age-group swimmers, who must attend school classes during the day. Many of these swimmers have no

If I sleep more will I perform better? choice but to practice in the pre-dawn hours, if they are to put in sufficient training time—but a 4 am wake-up call can make eight hours of sleep nearly impossible for those with busy schedules, especially if evening practices end late. Planning practice schedules carefully to avoid excessive impact on sleep time, either early in the morning or late in the evening, is clearly vital. Effective scheduling may also implement the concept of “sleep banking.” This involves including periods in which swimmers sleep extra hours to compensate for periods in which they must sleep less, because of training pressures. Research involving military personnel has shown that subjects improved in all psychomotor vigilance tasks when seven-day and five-day sleep-banking periods bracketed a seven-day period of sleep deprivation, during which subjects slept only three hours per night.1 Such a design may be impractical for a swim training program, but the general principle remains— swimmers should exploit whatever opportunities they can to “sleep bank.”

Effects of sleep deprivation • Sleep deprivation can impact autonomic nervous system function, leading to symptoms of overtraining syndrome. • A reduction in periods of deep sleep, when growth hormone is normally released, can lead to impaired tissue regeneration and development. • Reduction in quality and quantity of sleep Training may increase release of inflammatory cytokines, leading to weakened immune system function. • Athletes who sleep less than 8 hours per night are 1.7 times more likely to suffer injury. • Diminished cognitive function in alertness, reaction time, memory, and decision making is Sleep associated with a lack of sleep. • Perceptual and motor learning following training continue during sleep, so insufficient sleep leads to poor retention of new techniques and strategies.

120

Dryland Training

g Sleeping it off

Training

Evidence suggests that most athletes, including swimmers, sleep far less than eight hours per night, despite the fact that the numerous negative effects of sleep deprivation are well documented. These include decreased autonomic nervous system function, immune function and cognition, and increased symptoms of overtraining syndrome and risk of injury. Nervous system recovery, musculoskeletal regeneration, and immune robustness are all basic physiological processes that occur naturally in the training recovery process but are undermined when sleep is inadequate. Indeed, sleep has been described as the cheapest, most effective recovery modality available—while many swimmers spend significant money on supplements and recovery tools, sleep is hardwired into our behavior from birth.

Sleep banking Monday

Tuesday

Wednesday

Thursday

4 am 5 am 6 am 7 am

Friday

Saturday

Sunday Sleep Practice School Swim meet

8 am 9 am 10 am 11 am noon 1 pm 2 pm 3 pm 4 pm 5 pm 6 pm 7 pm 8 pm 9 pm 10 pm 11 pm midnight 1 am 2 am 3 am 4 am

Sleep hygiene Sleep hygiene is a critical, yet often overlooked, part of the sleep equation. Darkness and a cool temperature are both recommended as the best conditions to encourage sleep. Also of concern is the role of electronics. There is some evidence that electronics such as cell phones and tablets can disrupt normal sleeping patterns. Weaning anyone from their devices may be impossible these days, but at the very least, wherever the swimmer sleeps should not be a place where they are also playing on their phones or other devices.

o Banking on it Modifying practice schedules to incorporate “sleep banking” is one way to try to combat the negative impacts of long swim training hours on sleep patterns. The chart shows an example of this kind of planning, for an age-group swim team—notice the greater amount of sleep time allocated on Sundays, including an afternoon nap. Some swimmers have difficulty calming down sufficiently after evening sessions to fall asleep quickly, which is important if they have an early wake-up. If this pattern repeats week on week, swimmers can enter a zone of insufficient recovery, so it’s key to allow an adequate period between the end of evening training and “bed time,” wherever possible. If naps are possible mid week, then swimmers should certainly take advantage of that opportunity. 121

Does dryland aerobic training improve swimming performance?

Aerobic training may also reduce swimmers’ benefits from dryland strength training. Though scientific research is still seeking to define a specific rule for the relationship between aerobic and strength training on land, in reality each swimmer’s adaptation will be different, as will the specific circumstances in which the training is applied. Overall though, the potential benefits from supplementary aerobic training may be outweighed by the potential risks of impairing strength-related dryland gains. Another practical consideration is that aerobic land activities, especially those involving repeated strain, may cause injury in swimmers. For example, by default, running tends to be the aerobic dryland activity of choice, in part because it is much cheaper and more convenient than rowing, cycling, or crosscountry skiing. The problem with running is that swimmers can easily develop repetitive use injuries. So, despite the lack of convenience, dryland programs should prioritize lower impact modes of aerobic training such as rowing or cycling.

122

Dryland Training

There are circumstances in which dryland aerobic training may be useful. For example, if a team has restricted pool hours and can’t train at the level they need in the water, supplementary aerobic activities may fill that gap. Supplementary aerobic dryland can also help swimmers maintain general aerobic fitness during off-season or recovery blocks, while providing a mental respite from staring at the black line.

Timing for performance

g All in the timing

10 B

9 Increase in oxygen uptake per minute, VO2 max (%)

Most would agree that strength training has a role in a dryland program, but what about supplemental aerobic training such as cycling, running, rowing, and even swim bench training (see pages 116–117)? Swimmers already perform high volumes of in-pool aerobic exercise, and walk such a fine line between being optimally prepared and suffering overtraining that additional dryland cardio work might easily put them over the edge. Assuming that a team is training at a high level in the pool, one would expect their training tolerance to be at or near its maximum. And since the transferability of benefits from many dryland activities to swimming is unproven, the point of diminishing returns from such cross training may arrive earlier than expected.

Will I swim better if I run, bike, or go to spin class?

8 7 6 C

5 4 3 2 1

D

Not only are order, timing, and frequency of training modalities critical to ensure aerobic training does not impair strength gains, these guidelines are also key for maximizing the benefit of the aerobic training, as the interference effect works both ways. In one study, a 24 h gap between strength and cardio training appears to result in the greatest improvements in VO2 max, a common measure of cardiovascular endurance.1 Another study showed that weekly maximal strength training sessions did not negatively influence endurance performance in a competitive swimmers’ program, suggesting that more frequent intervention may indeed have an adverse effect. 2

A

0 A Strength training only B 24 h gap between strength and cardio training C 6 h gap between strength and cardio training D No gap between strength and cardio training

Planning strength and aerobic training sessions

C

B A

30

Relative strength improvement (%)

C

D

25

B

B D

20

A

A

C D

C 15 A

B D

10 Countermovement jump

5 Bench row 0 Half squat A Strength training only

B 24 h gap between strength and cardio training C 6 h gap between strength and cardio training Bench press

o Mind the gap The degree to which cardio or aerobic training may diminish the benefits of strength training in a concurrent program appears to depend on the timing of sessions focused on each modality. It is not enough to place the strength session before any aerobic session to minimize the interference effect. Research has shown that when there is no rest time between strength and cardio training, strength gains are reduced compared to athletes who underwent strength training only. At least six hours between strength and aerobic sessions

D No gap between strength and cardio training

appears to be optimal so that the two sessions don’t adversely affect each other, and indeed under these circumstances the cardio training appears to enhance the strength gains achieved.1 Since maximal strength training has been found to be an effective protocol in improving swim performance,2 it’s important to plan cardio training carefully—both in and out of the pool—so as not to undermine strength gains. Overall, aerobic dryland training should be kept to two sessions per week at most, to avoid interference and overtraining.

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Proper nutrition can have an important impact on the overall health, robustness, composition, and resiliency of a swimmer, as well as having direct performance and training enhancing effects. The implementation of sport nutrition principles such as appropriate caloric intake, specific nutrient intake and distribution, fluid and electrolyte balance, and appropriate supplementation, is essential to optimize the performance of a competitive swimmer. Furthermore, consideration of how an optimal nutrition program may vary depending on circumstances, individual preferences, physical and mental needs, and fluctuations in the athlete’s training and competition schedule, allows for the effective implementation of these principles for individual swimmers across the course of their athletic career.

chapter five

nutrition Kevin Iwasa-Madge

What are the caloric requirements for swimming?

How much should I eat to swim better?

Swimming is a form of physical activity that requires the activation of a broad range of muscles in the body. As for any exercise that requires a large amount of muscular activation, energy expenditure during swimming will be relatively high. According to the Compendium of Physical Activities, swimming has a metabolic equivalent (MET) of 6–11 METs depending on the stroke and intensity of swimming.1 This means that a swimmer will expend 2.5–5.0 Calories per pound of body mass per hour of swimming (6–11 kcal/kg/h). For an average-sized swimmer of 180 lb (82 kg), during an hour of swimming, this is anywhere from 450 to 900 Calories. (Keep in mind that during prolonged practices, a swimmer is unlikely to be swimming constantly, or at higher intensities, for the entire time.) Combine this rate of energy expenditure with the volume of training that many swimmers undergo, as well as the increased metabolic demand placed on a swimmer in order to physiologically adapt to their training, and the energy requirements of swimmers can be quite inflated. Swimmers need to consume a huge number of Calories in food in order to meet these energy expenditure and metabolic demands. We often use the term “Calories In” to refer to the caloric intake of a swimmer, in conjunction with the term “Calories Out” referring to the energy expenditure and metabolic demands.

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Submersion in cold water can lead to increases in resting metabolism as the body increases metabolic heat production in an attempt to maintain core body temperatures. The increase in resting metabolism is proportional to the decrease in core body temperature. Additionally, the relative energy cost of exercise can be higher in colder water because oxygen delivery can be reduced.2,3 Practically speaking, all of this additional swimming-specific energy expenditure needs to be replaced through increases in caloric intake.

d Staying hungry

It seems evident that swimmers have increased energy requirements over a more sedentary population, and anecdotal evidence certainly highlights increased appetites. Swimming may lead to increased energy requirements and appetite stimulation over other forms of exercise as well, although currently there is little research evidence directly confirming this. A logical and suggested mechanism for this could be related to the temperature of the water in which swimmers train. Exercising in cold water may lead to increases in appetite (although increases have not shown to be statistically significant in studies), which could be due to hungerregulating hormonal factors. Additionally, it could simply be a response to increased energy expenditure because of the bodycooling effect. Regardless of the mechanism, it is clear that swimmers have both an increased energy requirement, and a greater appetite, following swimming.4

Energy intake

ivity group)

No activity (control group)

mming

After swimming 1500 1500 Energy intake Kcal)

Energy intake (kcal)

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Nutrition

2000 2000

2500 2500

a All in the balance

NEED TO KNOW Calories and calories A calorie (cal) is a unit of energy, defined specifically as the amount of energy required to raise the temperature of 1 g of water by 1°C. Just as 1 km = 1000 m, and 1 kg = 1000 g, 1 kilocalorie (kcal) is equal to 1000 cal. Following the definition above, 1 kcal is the energy required to raise the temperature of 1 kg of water by 1°C. Although a calorie (cal) is 1000th of a kilocalorie (kcal) a Calorie (Cal), with a capital “C,” is the same as a kilocalorie. The two terms are used interchangeably, so 1 Cal = 1000 cal. Virtually all nutrition work uses Cal or kcal. Even if a piece of writing does not capitalize cal, it is still likely to be referring to a Cal or kcal. Metabolic equivalent of task (MET) Metabolic equivalent of task is a way of comparing the energy costs (calorie requirements) of different physical activities. We take the energy equivalent expended by a person seated quietly at rest to be 1 MET. If you’re carrying out an activity with a MET value of 3, this means you are expending 3 times as much energy (in other words, using 3 times as many Calories) as you would when resting.

The relative magnitudes of “Calories In” and “Calories Out” determine the adequacy of a swimmer’s fueling in the short term, and body mass in the longer term. Improvement in body composition—whether involving fat loss and muscle gain, or just fat loss and maintenance of lean tissue—can lead to long-term performance improvement down the road because there is less weight to pull through the water. But weight loss is a slow process, and while going through it the athlete will have less fuel available, so short-term performance may suffer. For this reason, if body composition is an issue, a Calorie deficit should be created months in advance of any major competition, with the swimmer then ramping up caloric intake again leading into the competition to ensure optimal fueling, with the added benefit of being lighter.

Calorie intake and expenditure

A

A When Calorie intake and expenditure are equal, there is a state of caloric balance, in which there is no net weight gain or loss. However, this does not mean that a swimmer cannot be losing or gaining body fat, as well as losing or gaining lean tissue. B When Calorie intake falls short of expenditure, a swimmer will experience a net loss in body mass. This could be a loss in body fat, or muscle, or both. It is even possible to gain muscle or fat, while still experiencing a net weight loss (e.g. a gain of 1 lb muscle + a loss of 2 lb fat = net loss of 1 lb). Inadequate Calorie intake is usually associated with an acute decrease in performance, due to suboptimal fueling and adaptation. This is not to say that reduced Calorie intake cannot be a part of long-term improvements in performance, as ideal body composition is necessary to optimize performance.

B

C When “Calories In” exceed “Calories Out,” swimmers experience a net gain in body mass. Again, this can result in a gain of lean tissue, or body fat, or both. A proportionately larger gain in one tissue type can also occur simultaneously with a loss in the other tissue. This scenario is more often associated with a short-term optimizationof performance, as a result of adequate fueling, but should be monitored so as to not alter body composition in the long term. Calories In = food and beverages Calories Out = metabolic rate and energy expenditure

C

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Can eating habits affect muscle synthesis rate? Protein is one of the three macronutrients, the other two being carbohydrate and fat. Like all macronutrients, proteins are huge molecules made up of hundreds of sub-units, or “building blocks,” linked together. In proteins, the building blocks are called amino acids. Protein makes up the majority of muscle in the body, which we use for swimming and other activities—an essential nutrient that is required in abundance. While a typical “healthy” daily intake for an average individual is somewhere around 0.3–0.5 g of protein per pound of body mass (or 0.7–1.1 g per kg), training athletes have much larger protein requirements. Most athletes (and swimmers are no exception) need upward of 0.5–0.8 g of protein per pound of body mass per day (1.1–1.8 g per kg per day) to ensure their system is receiving adequate nutrients to repair CH5 SP1 G2 muscle damage from vigorous swimming and elicit adaptation to training stimuli.

How much protein do I need? In other words, swimmers need protein to recover from their last swimming session and to become a better swimmer over time. An average adult swimmer of about 180 lb (82 kg), for example, should be aiming for around 140 g of protein every day.1 That’s equivalent to about 23 large eggs, or six small chicken breasts! Approximately 20 g of protein (1 chicken breast) per feeding (for an average-sized athlete) seems to be the threshold mass required to stimulate a maximal rate of muscle synthesis (building and adapting muscle) for a period of time around 2–3 hours. This means that meals containing less than this amount of protein may not optimize the rate at which the body repairs muscle and adapts to a training stimulus. So swimmers should aim to reach 20 g of protein per feeding. Interestingly, though, meals containing more protein than this will not likely elicit a rate of muscle synthesis that is significantly stronger.2

Muscle synthesis responses to resistance training

g Body building

0.15 0.15

Muscle synthesis (% per h)

Muscle synthesis (% per h)

This bar chart represents some results from a study looking at rates of muscle protein synthesis after resistance training.3 Immediately following intense resistance training, subjects consumed a drink containing 0, 5, 10, 20, or 40 g of protein. Biopsies were then taken after 1 and 4 hours to measure muscle synthesis. In the sample of young male athletes studied, the rate of muscle synthesis after exercise increased in response to increasing dietary protein. Above 20 g of protein, the relationship between muscle synthesis rate and quantity of protein hit a point of diminishing return – larger amounts of ingested protein did not result in significantly higher rates of muscle synthesis. Larger protein meals may elicit a maximal muscle synthesis rate for a slightly longer time, but to a limited extent only.

0.10 0.10

0.05 0.05

0

128

0

00

Nutrition

55

10 10

20 20 Protein ingested ingested )g) (g) Protein

40 40

Muscle synthesis responses to eating patterns B 0.1 Anabolic 1.0

0.5 0.5

0.5 0.5

Anabolic

0.1 Anabolic 1.0

Anabolic

A

a Little and often

D

0.1 Anabolic 1.0

0.5 0.5

0.5 0.5

0

00

Anabolic

size of the athlete, the type and amount of training, 0.1 Anabolic 1.0 and preferred styles of fueling.

Anabolic

6

am

a6m am 99 ama m non oono n 33 pmp m 66 pmp m 99 m pmpm odm niidn ghig tht 33 amam

C

99 ama m non oono n 33 pmp m 66 pmp m 99 m pmpm odm niidn ghig tht 33 amam

a6m

6

Catabolic

Catabolic

These graphs represent muscle synthesis responses to different eating patterns for an 0 0 average (180 lb/82 kg) swimmer.4 The gray areas represent the anabolic response to ingested protein, and the blue represents the eventual catabolic state CH5 SP1 G1 –0.5 –0.5 -0.5 -0.5 CH5 SP1 G1 between meals. The vertical axis shows a relative scale of muscle synthesis, where +1 signifies a maximal Catabolic anabolic response and –1 represents maximal Catabolic -1.0 –1.0 –1.0 -1.0 catabolism. A variety of eating patterns can accomplish both adequate protein intake and effective protein timing. A single 140 g meal is not an efficient way of Three meals per day, each of 10–15 g protein Three meals per day, each of 20–30 g protein 10–15 g of protein in a given meal is a suboptimal 20–30 g of protein in a given meal is adequate to achieving adequate muscle recovery or adaptation, as amount to maximize an anabolic or muscle synthesis maximize the anabolic or muscle synthesis response the muscle synthesis response will not last the whole response. for a short time. However, only three meals may not day, despite the meal providing a whole day’s worth of provide adequate daily protein to optimize muscle recovery and adaptation throughout the day. protein. Athletes are better off utilizing a basic protein timing strategy, where protein is ingested in at least C D three meals per day, depending on the meal size, the

Catabolic

99 ama m non oonon 33 pm pm 66 pm pm 99 m pm odm pm nidi n gihg tht 33 amam

m

a6m

6

Five meals per day, each of 20–30 g protein This frequent, pulse-like intake of 20–30 g of protein results in adequate daily protein intake and meets the minimum threshold quantity of protein to establish a maximal anabolic or muscle-synthesis response to each meal.

-1.0 –1.0

a6 ma

Catabolic

am

Catabolism, on the other hand, refers to the metabolic processes leading to the Catabolic -1.0 –1.0 breakdown of tissue.

-0.5 –0.5

6

-0.5 –0.5

99 ama m non oono n 33 pmp m 66 pmpm 99 m pmpm odm nidi n ghig tht 33 amam

Anabolism encompasses the metabolic pathways that lead to tissue growth (so muscle anabolism is good for an athlete, while fat anabolism is not usually desirable).

Catabolic

NEED TO KNOW

Four meals per day, each of 30–40 g protein The eating pattern illustrated here also results in adequate daily protein similar to graph C. This approach involves a smaller number of larger meals to meet protein requirements.

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How does carbohydrate and fat intake affect substrate utilization?

Should I get my energy from carbohydrate or fat? Internal carbohydrate stores can be maximized through a high-carbohydrate diet, providing around 3–5 g of carbohydrate per pound of body mass per day (7–11 g per kg per day). A low-carbohydrate, high-fat diet may not maximize carbohydrate stores even if it is isocaloric (provides the same number of calories). In addition to adequate carbohydrate intake throughout the day, consuming carbohydrate before and during training has been utilized to increase carbohydrate availability, thereby delaying exhaustion and improving performance in competition.

Swimmers rely primarily on two sources of energy, or substrates, when swimming and training. These are carbohydrate and fat. We can further subdivide these into two categories—endogenous (internal) and exogenous (external) sources. Our internal sources of carbohydrate are blood glucose and glycogen, while our internal source of fat is our body fat. External sources of both carbohydrate and fat come from our diet. Carbohydrate utilization is typically limited by the quantity of carbohydrate a swimmer is capable of storing, while fat utilization depends the rate at which a swimmer can oxidize fat for energy.

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Assuming a caloric intake that matches energy expenditure, a swimmer needs to determine how to distribute these calories across these two macronutrients (in addition to an obligatory number of calories from protein). When making this decision, it is important that the swimmer determines whether the goal is performance related or weight management related. In other words, are you swimming to compete or swimming to lose weight?

However, these carbohydrate-fueling strategies decrease fat oxidation at a given intensity during a low to moderate volume of training. If fat loss (rather than performance) is the primary goal, then a carbohydrate-fueling strategy may be counter productive. Isocaloric high-fat diets, on the other hand, can lead to a “fat-adapted” metabolism, allowing for increased rates of fat oxidation.1

Carbohydrate for performance As the intensity of swimming increases, the swimmer’s reliance on carbohydrate as a fuel source increases. So, at higher intensities, carbohydrate availability (glycogen in this case) is Low-carbohydrate, the primary factor in determining time to exhaustion. In other words, at higher intensities, a fit swimmer will be able to swim high-fat diet for as long as stored carbohydrate lasts.

Low-carbohydrate, high-fat diet

a High-performance fuel

For swimmers who are looking to optimize performance at relatively high intensities (70% VO 2 max and higher), which is High-carbohydrate, the case for most swimming events, it is key to ensure adequate carbohydrate diet availability.2 The amount of carbohydrate we store can be optimized with a high-carbohydrate diet of around 3–5 g/lb body mass/day. (Note that the actual times to exhaustion may vary depending on a number of variables, including fitness level.)

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Nutrition

High-carbohydrate diet

0 0.5 Time to exhaustion (min) at 70% VO2 max

1.0

0 0.5 1.0 Time to exhaustion at 70% VO2 (min)

1.5

1.5

Nutrition for high and low intensity

a Feeding the fire

This bar chart compares substrate oxidation rates during 20 minutes of relatively high intensity exercise (at 70% VO2 max) for athletes who experienced acute intake of carbohydrate before and during training (50–100 g per hour of swimming) and for athletes who underwent no such carbohydrate fueling. The carbohydrate-fueling strategy appears to enhance the rate at which carbohydrate is utilized, but decreases fat oxidation rates.2 (Again, actual rates are dependent on a number of variables, including fitness level.)

Fat

Carbohydrate 0

0.5

1.0

2.0 1.5 Substrate oxidation (g/min)

3.0

2.5

3.5

No carbohydrate fueling before or during training Acute carbohydrate intake before and during training

a Slow burn

This chart compares substrate oxidation rates after six hours of exercise. Although swimmers do not utilize fat for energy at higher intensities very well (>70% VO2 max), they can utilize fat for energy at lower intensities. When carbohydrate stores become depleted due to prolonged swimming, and swimming intensity is relatively low (