Biomechanics of Sport Editor Christopher L. Vaughan, Ph.D. Associate Professor of Bioengineering Clemson University Clemson, South Carolina 0 CRC Press Taylor & Francis Group Boca Raton London New York CRC Press is an imprint of the Taylor & Francis Group, an informa business CRC Press Taylor & Francis G roup 6000 B roken S ound Parkway N W, Suite 3 00 Boca Raton, FL 33487-2742 © 1989 b y T aylor & Francis G roup, LLC CRC Press i s a n i mprint of Taylor & Francis G roup, an In forma business No claim t o o riginal U.S. Government w orks This book contains information obtained from authentic and highly regarded sources. Reasonable efforts have been made to publish reliable data and information, b ut the author and publisher c annot assume responsibility for the validity o f all materials or t he c onsequences o f their u se. 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(CCC), 222 Rosewood Drive, Danvers, MA 01923, 978-750-8400. CCC is a not·for· profit organization t hat provides licenses a nd registration for a v ariety o f users. For organizations t hat have been granted a photocopy l icense by the C CC, a separate system o f payment has been arranged. Trademark N otice: Product o r c orporate n ames m ay b e t rademarks o r r egistered trademarks, and a re used only for identifica­ tion a nd e xplanation w ithout intent t o i nfringe. Visit t he T aylor & Francis W eb s ite a t http://www.taylorandfrancis.com and t he C RC P ress W eb s ite a t http://www.crcpress.com PREFACE Biomechanics may be considered as the science that studies the external forces acting on the human b ody a nd t he e ffects p roduced b y these f orces. Sport i s o ne a rea w here a k nowledge of biomechanics could be of vital importance. This applies both to the improvement of performance and to the etiology and thus prevention of s ports-related injuries. Although biomechanics research, and specifically research on sport, has been carried out for many decades, the formation of n ational and international bodies is of c omparatively recent origin. The Journal of Biomechanics was launched in 1968, while the International Society of Biomechanics, after a number of biannual congresses, was officially constituted in 1973. This has been followed by societies being set up in the U.S. ( 1977), Canada ( 1980), and Europe (1980) . The latest development has been the introduction of t he International Journal of S port Biomechanics, which first appeared at the beginning of 1985. All these societies and journals play a major role in disseminating knowledge on biomechanics, and particularly as this knowledge pertains to sport. The present volume is complementary to the activities of t he societies and journals. It i s hoped that it will not only provide a basis of k nowledge, but also act as a stimulus for further progress. Since there are many different sports practiced worldwide, the volume quite obviously has had to be selective. This has been dictated by two main factors: a sufficient body of research knowledge for a particular sport, and the availability of authors. Thus, a selection of i mportant topics has been chosen. However meaningful the title and their topics seem to be, the eventual value of t he volume is to a large extent determined by the value of t he separate contributions. I therefore wish to thank and acknowledge all the authors for their hard work, because without their cooperation, this volume would never have been published. It is my fervent hope that their efforts will be rewarded by inspiring those already in the field of sports biomechanics, or perhaps those wishing to join, to extend our knowledge in this exciting field. In Chapters 1 to 4, the cyclic activities are covered. In Chapter 1, the authors address some of t he substantive issues in running. Swimming (in Chapter 2) is discussed from the vantage point o f the forces (both propulsive and resistive) acting both on animals and humans. Another aquatic sport, rowing and sculling, is covered in Chapter 3. Subsequently, the biomechanics of s peed skating are reviewed in Chapter 4 from a modeling perspective. In Chapters 5 to 9, a variety of d ifferent sports activities are covered. In Chapter 5, the use of weights (machines, training, and lifting) is extensively and critically analyzed. The throwing events in track and field (shot, discus, and javelin) are studied in Chapter 6. In Chapter 7 , t he emphasis is placed on developing training programs for ski-jumping, alpine­ and c ross-country s kiing a nd a lso N ordic c ombination s kiing. The m echanics o f tennis s trokes and equipment are reviewed in Chapter 8, while in Chapter 9, t he mechanics of c ycling are analyzed. The publication of t his volume could not have been achieved without significant contri­ butions from various individuals and institutions. It therefore gives me great pleasure to acknowledge the following: the authors, without whom the volumes would not exist; CRC Press, and particularly Marsha Baker, for their patience when deadlines were continually being extended: Groote Schuur H ospital and the University of Cape Town f or providing me with the necessary facilities and time; the Association o f Sports Science and Medical Research Council of South Africa, for providing financial assistance; Carien Coetzee for her substantial secretarial assistance; and my family who endured many hours of w ork, but provided en­ couragement when it was most needed. Kit Vaughan THE EDITOR Christopher L. (Kit) Vaughan, P h.D., is a graduate o f Rhodes University, South Africa, with a B.Sc. in Physics and Applied Mathematics (1974). In 1975 he completed the B.Sc. (Hons) degree in these subjects and wrote his thesis on a biomechanical model of running. After working as a research officer at the Applied Physiology Laboratory of t he Chamber of Mines in Johannesburg ( concentrating o n heat-exchange p roblems in exercise), he enrolled as a student at the University of I owa. There he majored in biomechanics, anatomy, and exercise physiology, obtaining his Ph.D. degree in 1980 with a dissertation entitled "An optimization approach to closed-loop problems in biomechanics". While at Iowa, he acted as a consultant to the Nissen Corporation with emphasis on weight training and trampoline equipment. Between 1980 and 1986, Dr. Vaughan was on the joint staff o f G roote Schuur Hospital and the University of C ape Town Medical School in the Department of B iomedical Engi­ neering. There he held the titles of Specialist Medical Scientist (Biomedical Engineer) and Senior Lecturer. During this period he initiated and taught a course on the biomechanics of sports techniques and injury mechanisms to candidates for the B.Sc. (Medicine) (Hons) degree in Sports Science. In 1983, Dr. Vaughan spent his sabbatical leave as a Research Associate at the University of O xford Orthopaedic Engineering Centre in England concen­ trating on j oint forces during human walking. Since October 1986 he has been an Associate Professor in Clemson University's Department of B ioengineering, where he is responsible for orthopedic b iomechanics a s well as being the academic c oordinator f or the Bioengineering Alliance of S outh Carolina. Dr. Vaughan has published in major international journals on a variety of t opics. These have included the fields of both orthopedic and sports biomechanics. He is a charter member of t he American Society of B iomechanics, and since 1979 he has attended, and presented papers at, the biannual congress of t he International Society of B iomechanics. CONTRIBUTORS Antonio Dal Monte, M.D. John W. Kozey, M.Sc. Head Director of R esearch Department of P hysiology and Orthopaedic and Sports Medicine Biomechanics Clinic of N ova Scotia Institute of S ports Science Halifax , Canada Italian National Olympic Committee Rome, Italy R. Bruce Martin, Ph.D. Professor and Director R. W. De Boer, M. Sc. Orthopaedic Research Laboratory Department of E xercise University of C alifornia at Davis Physiology and Health Davis, California Academic Medical Centre Amsterdam, The Netherlands Dirk J . P ons, M. Sc. Research Associate G. De Groot, Ph.D. Department of B iomedical Engineering Department of E xercise University of C ape Town Physiology and Health Medical School Observatory Academic Medical Centre Cape Town, S. Africa Amsterdam, The Netherlands Carol A. Putnam, Ph.D. Bruce C. Elliott, Ph. D. Assistant Professor Senior Lecturer School of P hysical Education Department of H uman Movement Dalhousie University and Recreation Studies Halifax, Canada University of W estern Australia Perth, Australia Gert J . van Ingen Schenau, Ph. D. Department of F unctional Anatomy John Garhammer, Ph. D. Faculty of H uman Movement Sciences Associate Professor Free University Departmentof Physical Education Amsterdam, The Netherlands California State University Long Beach, California Christopher L. Vaughan, Ph. D. Associate Professor of B ioengineering Mont Hubbard, Ph. D. Clemson University Associate Professor Clemson, South Carolina Department of M echanical Engineering University of C alifornia at Davis Davis, California Kazuhiko Watanabe, M. D. Associate Professor Andrzej Komor, Ph. D. Laboratory of P hysiology Department of B iocybernetics and Sports Biomechanics Institute of S port University of H iroshima Warsaw, Poland Hiroshima, Japan TABLE OF CONTENTS Chapter I Substantive Issues in Running . ..... ...................................................... I C. A. Putnam and J . W. Kozey Chapter 2 Swimming: Forces on Aquatic Animals and Humans .................................... 35 R. Bruce Martin Chapter 3 Rowing and Sculling Mechanics ........ ................................................ 53 A. Dal Monte and A. Komor Chapter 4 Biomechanics of S peed Skating ............ ............ ............ .. .... .............. I 2I G. J. van lngen Schenau, R. W. De Boer, and G. De Groot Chapter 5 Weight lifting and Training ......................................... ................... I69 J. Garhammer Chapter 6 The Throwing Events in Track and Field ............................................... 213 M. Hubbard Chapter 7 Ski-Jumping, Alpine-, Cross-Country-, and Nordic-Combination Skiing ............... 239 K. Watanabe Chapter 8 Tennis Strokes and Equipment . ....... ................................................. 263 B. C. Elliott Chapter 9 Mechanics of Cycling .................................................................. 289 D. J. Pons and C. L. Vaughan Index .... .. ................................................. ........... .............. ... 317 I Chapter I SUBSTANTIVE ISSUES IN RUNNING Carol A. Putnam and John W. Kozey TABLE O F CONTENTS I. Introduction .. ........ ............ ..................... ....................... .... . 2 II. Running Efficiency .................................. ............... .............. 2 A. Measuring Mechanical Work Done . .... ... ........ ....... .... ...... ....... 3 I. Work Done by Internal Forces . ... ... .. .. ..... .............. .. . .. .. 3 2. Work Done by External Forces ... . .. .. ........ .. .... .. ........ .. .. 5 B. Interpreting Mechanical Efficiency ........................................ 5 I. Work Done by RJMs vs. Individual Muscles . ...... . .... ...... .. .. 5 2. Type of Muscle Contraction ....................................... 5 3. Storage and Reutilization of E lastic Energy . ........ .... ... ........ 6 4. Nonmuscular Force Contribution to RJMs ................... ...... 7 C. Muscular Effort ........................................................... 7 D. Apparent Efficiency ....................................................... 7 E. Summary ................. ................................................. 7 III. Running Economy ... ............................................................. 8 IV. External Forces .... .... ... .... .................... ... .. ........... .. .. ..... ....... 9 A. Air Resistance . ............................................................ 9 B. Ground-Reaction Force ... .. ............... .. .. .... ....... .... ..... .. .... 1 0 V. Muscle Function in Running ..................................................... II A. Resultant Joint Moment Patterns .... ..................................... II I. Hip Moment ....................... ............................... 13 2. Knee Moment. .... . . .. . . . .. ...... .. ...... ......................... 1 3 3. Ankle Moment ........... ........ ............................... .. 14 4. Summary ......................................................... 14 B. Functional Significance of RJMs and Segment Interaction ............... 14 C. Simulation of Running Gait .............................................. 1 6 D. Electromyography ............. ..... ...................................... 1 6 1. Hip Musculature .................................................. 17 2. Knee Musculature ..................... ............................ 17 3. Ankle Musculature . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17 4. Co-contraction ................. ................................... 19 E. Muscle Length Changes .................................................. 19 VI. Performance Improvement ....................................................... 20 VII. Running Injuries ...................................................... ....... .... 2 1 A. Sports Medicine .......................................................... 21 1. Patello-Femoral Syndrome . ....................................... 2 2 2. Achilles Tendinitis . ............................................... 23 3. Hamstring Strains . ................................................ 23 2 Biomechanics of Sport B. Biomechanical Measurement and Injuries ................. ........ ....... 24 1. Force Platform Data ......... .......... .. ....... .... ...... ..... ... 24 2. Pressure Transducer Data . ........ .............................. .. 25 3. Electrogoniometer Data .. ...................... ....... .......... .. 26 4. Accelerometer Data . ...... ........................................ 26 VIII. Summary ................... ..................................... .......... ...... 27 References . .. .. ........................... ........ .. ............. ... ... .. .. .... ... .... .. . 2 8 I. INTRODUCTION Running h as r eceived c onsiderable a ttention f rom researchers i n b iomechanics, particularly over the last several decades. The number of publications or presentations at scientific meetings escalates yearly, adding to the more than 600 reported studies dealing with me­ chanical aspects of r unning. In addition, biomechanical considerations of r unning are being featured in popular journals with increased frequency, attempting to satisfy the curiosities of t housands of r ecreational and competitive runners about the mechanical implications and effects of r unning. Consistent with the proliferation of l iterature in this area, several extensive reviews have been published. '·4 The p resent paper is written t o augment and update these reviews a lthough some overlap will necessarily exist. Research into the biomechanics o f r unning is suffering the growing pains of b eing dom­ inated by descriptive studies. While recognizing the importance of a n extensive descriptive foundation, several investigators257 have emphasized the importance of a ddressing more • mechanistic issues - What fundamentally dictates the way we run? What forces are re­ sponsible for observed running patterns? What criteria dictate optimal performance? What are the mechanisms of i njury? - etc. In the present paper we will attempt to review the literature on running mechanics in light of p otential answers to t h ese questions. In the 1920s a nd 1930s, several papers, considered b y m any t o b e c lassics, were p ublished which dealt with some of t he basic, mechanistic aspects of r unning.8 11 It is encouraging - that the attention of p resent day researchers is being directed more and more towards these issues. Through these efforts we should start to see the development of a theoretical frame­ work out of w hich should emerge general biomechanical principles relating to the funda­ mental mechanisms of h uman motion. 12 It is impossible to understand fully the fundamental mechanisms of r unning from a bio­ mechanical perspective without crossing over into several disciplines, including cardiovas­ cular p hysiology, neuromuscular p hysiology, anatomy, and motor c ontrol. Space c onstraints make it impossible to span these areas in the present review so that the discussion will be restricted to a mechanical perspective o f r unning. The r eader i s directed t o a n excellent b ook recently brought out by McMahon13 entitled Muscles, Reflexes, and L ocomotion, in which many aspects critical to the fundamental understanding of running are presented in an integrated and lucid manner. II. RUNNING EFFICIENCY If o ne questioned runners or r esearchers interested in the mechanics of r unning on what fundamentally d ictates t he w ay w e r un, the answer w ould p robably b e efficiency. Efficiency, 3 defined as the ratio of mechanical work done to metabolic energy expended 13 14 is one of • the most extensively researched, yet poorly understood concepts of r unning mechanics. The problem o f measuring e fficiency is one that r equires c lose c ooperation b etween biomechanists and exercise physiologists, and is complex from both perspectives. 2 15 For the biomechanist, • the challenge lies in correctly measuring mechanical work done and interpreting this measure in light of u nderlying principles which are likely to govern the way we run. A. Measuring Mechanical Work Done There is considerable confusion as to how mechanical work done should be measured. Much of t his confusion stems from the fact that work done has been quantified in terms of energy changes. As will be pointed out below, this has resulted in both ambiguous and inaccurate measures of mechanical work done in running and consequently running effi­ ciency. Several investigators have measured mechanical work done in running solely in terms of the work done to cause changes in the energy state o f t he total body mass center. 1 625 Winter26 - criticized t his approach in that it oversimplified t he system, and he suggested that t he findings of t hese studies should be regarded with caution. He pointed out that consideration must be given to the mechanical energy changes of i ndividual segments which are collectively re­ sponsible for changes in the energy state of t he total body mass center. He emphasized that by doing this, the mechanical energy associated with reciprocal actions of b ody segments, which have no net effect on the motion of t he total body center of m ass, are not ignored . One o f t he first attempts to account for mechanical energy changes of i ndividual segments in running was by Fenn.1027 He suggested that the mechanical work done on a runner was • the sum of t he work done to cause changes in the energy of t he total body center of m ass (potential energy and kinetic energy due to translation), generally referred to as external work, and the work done to cause mechanical energy changes of individual body segments (potential energy and kinetic energy due to translation and rotation), generally referred to as internal work. This technique has since been employed in several investigations of r un­ ning. 2833 This method of analysis treats segment motions as if they were independent of - each other and of the movement o f the total body mass center, which is clearly inappropriate. The body must be viewed instead as a constrained, linked system. As a result, the work done on the human body cannot be measured by changes in energies of i ndividual segments and/or the total body mass center in the general case. 3 4 Measures of mechanical work done on the human body require the identification of individual forces which actually do work on the system and a quantification of t he work done by these forces. Forces doing work on the human body system in running include those which arise from both internal and external sources. 1. Work Done by Internal Forces Internal forces applied to individual body segments include those exerted by muscles (or musculotendinous units), ligaments, joint capsules, and articulating surfaces. Since it is impossible to quantity these forces individually, 35 they are represented by a resultant joint force (RJF) and a resultant joint moment (RJM) associated with each joint of t he system. An RJF is the vector sum of a ll forces applied across or through a joint (including muscle, ligament, joint capsule and bony contact forces), while an RJM is the vector sum of t he moments of t hese forces measured relative to the joint center. Simplified in this manner, the kinetics of the linked segment system can then be solved via an inverse dynamics approach. The only internal forces that are associated with metabolic energy consumption are those exerted by muscles. The net effect of m uscle forces acting on a system of b ody segments are reflected primarily by the RJMs of t he system. It m akes sense, therefore, that work done by internal forces be calculated in terms of t he work done by the RJMs only. This was done