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Tóm tắt nội dung (trích từ tài liệu gốc): Fundamentals of Biomechanics Duane Knudson Fundamentals of Biomechanics Second Edition Duane Knudson Department of Kinesiology California State University at Chico First & Normal Street Chico, CA 95929-0330 USA dknudson@csuchio.edu Library of Congress Control Number: 2007925371 ISBN 978-0-387-49311-4 e-ISBN 978-0-387-49312-1 Printed on acid-free paper. � 2007 Springer Science+Business Media, LLC All rights reserved. This work may not be translated or copied in whole or in part without the written permission of the publisher (Springer Science+Business Media, LLC, 233 Spring Street, New York, NY
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Fundamentals of Biomechanics
Duane Knudson
Fundamentals
of Biomechanics
Second Edition
Duane Knudson
Department of Kinesiology
California State University at Chico
First & Normal Street
Chico, CA 95929-0330
USA
dknudson@csuchio.edu
Library of Congress Control Number: 2007925371
ISBN 978-0-387-49311-4 e-ISBN 978-0-387-49312-1
Printed on acid-free paper.
� 2007 Springer Science+Business Media, LLC
All rights reserved. This work may not be translated or copied in whole or in part without the written permission of the
publisher (Springer Science+Business Media, LLC, 233 Spring Street, New York, NY 10013, USA), except for brief excerpts
in connection with reviews or scholarly analysis. Use in connection with any form of information storage and retrieval,
electronic adaptation, computer software, or by similar or dissimilar methodology now known or hereafter developed is
forbidden.
The use in this publication of trade names, trademarks, service marks and similar terms, even if they are not identified as
such, is not to be taken as an expression of opinion as to whether or not they are subject to proprietary rights.
987654321
springer.com
Contents
Preface ix NINE FUNDAMENTALS OF BIOMECHANICS 29
Acknowledgments
xi Principles and Laws 29
PART I
Nine Principles for Application of
INTRODUCTION
Biomechanics 30
QUALITATIVE ANALYSIS 35
SUMMARY 36
REVIEW QUESTIONS 36
CHAPTER 1 KEY TERMS 37
INTRODUCTION TO BIOMECHANICS SUGGESTED READING 37
OF HUMAN MOVEMENT WEB LINKS 37
WHAT IS BIOMECHANICS? 3
WHY STUDY BIOMECHANICS? 5 PART II
Improving Performance 5
Preventing and Treating Injury BIOLOGICAL/STRUCTURAL BASES
Qualitative and Quantitative Analysis
9
WHERE CAN I FIND OUT ABOUT
BIOMECHANICS? 11 CHAPTER 3
Scholarly Societies
Computer Searches ANATOMICAL DESCRIPTION AND
Biomechanics Textbooks 12 ITS LIMITATIONS
BIOMECHANICAL KNOWLEDGE VERSUS 13 REVIEW OF KEY ANATOMICAL CONCEPTS 41
INFORMATION
Kinds of Sources 14
Evaluating Sources
A Word About Right and 15 Directional Terms 42
Wrong Answers
Joint Motions 43
SUMMARY
16 Review of Muscle Structure 46
REVIEW QUESTIONS
16 MUSCLE ACTIONS 49
KEY TERMS
18 Active and Passive Tension of Muscle 51
SUGGESTED READING
Hill Muscle Model 51
WEB LINKS
19 THE LIMITATIONS OF FUNCTIONAL
20 ANATOMICAL ANALYSIS 53
21 Mechanical Method of Muscle
21 Action Analysis 53
The Need for Biomechanics to
21 Understand Muscle Actions 56
22 Sports Medicine and Rehabilitation 60
Applications
RANGE-OF-MOTION PRINCIPLE 60
FORCE�MOTION PRINCIPLE 63
CHAPTER 2 SUMMARY 65
FUNDAMENTALS OF BIOMECHANICS REVIEW QUESTIONS 66
AND QUALITATIVE ANALYSIS
KEY MECHANICAL CONCEPTS 23 KEY TERMS 66
Mechanics 23 SUGGESTED READING 66
Basic Units 25 WEB LINKS 67
v
VI FUNDAMENTALS OF BIOMECHANICS
CHAPTER 4 OPTIMAL PROJECTION PRINCIPLE 117
MECHANICS OF THE ANGULAR MOTION 121
MUSCULOSKELETAL SYSTEM
Angular Velocity 122
TISSUE LOADS
69 Angular Acceleration 123
RESPONSE OF TISSUES TO FORCES
Stress 69 COORDINATION CONTINUUM PRINCIPLE 128
Strain
Stiffness and Mechanical Strength 70 SUMMARY 130
Viscoelasticity
70 REVIEW QUESTIONS 130
BIOMECHANICS OF THE PASSIVE
MUSCLE�TENDON UNIT (MTU) 71 KEY TERMS 131
BIOMECHANICS OF BONE 72
SUGGESTED READING 131
75 WEB LINKS 132
76
BIOMECHANICS OF LIGAMENTS 77
THREE MECHANICAL CHARACTERISTICS CHAPTER 6
OF MUSCLE 79 LINEAR KINETICS
Force�Velocity Relationship 79 LAWS OF KINETICS 133
Force�Length Relationship 84
Force�Time Relationship 86 NEWTON'S LAWS OF MOTION 133
STRETCH-SHORTENING CYCLE (SSC) 88 Newton's First Law and First
FORCE�TIME PRINCIPLE 92 Impressions 133
NEUROMUSCULAR CONTROL 94 Newton's Second Law 136
Newton's Third Law 137
The Functional Unit of Control: 94 INERTIA PRINCIPLE 139
Motor Units
95 MUSCLE ANGLE OF PULL:
Regulation of Muscle Force
Proprioception of Muscle Action QUALITATIVE AND QUANTITATIVE
and Movement 99 ANALYSIS OF VECTORS 141
SUMMARY 100 Qualitative Vector Analysis of
REVIEW QUESTIONS
101 Muscle Angle of Pull 141
Quantitative Vector Analysis of
KEY TERMS 101 Muscle Angle of Pull 143
SUGGESTED READING
WEB LINKS 102 CONTACT FORCES 145
103 IMPULSE�MOMENTUM RELATIONSHIP 147
FORCE�TIME PRINCIPLE 149
WORK�ENERGY RELATIONSHIP 151
PART III Mechanical Energy 151
MECHANICAL BASES Mechanical Work 155
CHAPTER 5 Mechanical Power 157
LINEAR AND ANGULAR SEGMENTAL INTERACTION PRINCIPLE 160
KINEMATICS
SUMMARY 164
REVIEW QUESTIONS 165
LINEAR MOTION 107 KEY TERMS 166
Speed and Velocity 109 SUGGESTED READING 166
Acceleration 113
Uniformly Accelerated Motion 115 WEB LINKS 167
CHAPTER 7 SUMMARY CONTENTS VII
DISCUSSION QUESTIONS
ANGULAR KINETICS SUGGESTED READING 224
WEB LINKS 224
TORQUE 169 224
225
SUMMING TORQUES 173
ANGULAR INERTIA (MOMENT OF INERTIA) 174
NEWTON'S ANGULAR ANALOGUES 178 CHAPTER 10
EQUILIBRIUM 179 APPLYING BIOMECHANICS IN
COACHING
CENTER OF GRAVITY 180
PRINCIPLE OF BALANCE 183 QUALITATIVE ANALYSIS OF
SUMMARY 189 THROWING TECHNIQUE 227
REVIEW QUESTIONS 190 QUALITATIVE ANALYSIS OF
DRIBBLING TECHNIQUE
KEY TERMS 190 228
SUGGESTED READING 191 QUALITATIVE ANALYSIS OF
CONDITIONING
WEB LINKS 191 230
RECRUITMENT 231
CHAPTER 8 QUALITATIVE ANALYSIS OF CATCHING 233
FLUID MECHANICS SUMMARY 234
DISCUSSION QUESTIONS 234
FLUIDS 193 SUGGESTED READING 234
FLUID FORCES 193 WEB LINKS 235
Buoyancy 193
Drag 195
Lift 200 CHAPTER 11
The Magnus Effect 203 APPLYING BIOMECHANICS IN
STRENGTH AND CONDITIONING
PRINCIPLE OF SPIN 208
SUMMARY 210
KEY TERMS 210 QUALITATIVE ANALYSIS OF
REVIEW QUESTIONS 210 SQUAT TECHNIQUE 237
SUGGESTED READING 210 QUALITATIVE ANALYSIS OF
WEB LINKS 211 DROP JUMPS 239
EXERCISE SPECIFICITY 240
INJURY RISK 242
PART IV EQUIPMENT 244
APPLICATIONS OF BIOMECHANICS SUMMARY 244
IN QUALITATIVE ANALYSIS
DISCUSSION QUESTIONS 245
CHAPTER 9 SUGGESTED READING 246
APPLYING BIOMECHANICS IN WEB LINKS 246
PHYSICAL EDUCATION
QUALITATIVE ANALYSIS OF KICKING 215 CHAPTER 12
TECHNIQUE 218
APPLYING BIOMECHANICS IN SPORTS
QUALITATIVE ANALYSIS OF BATTING 219 MEDICINE AND REHABILITATION
QUALITATIVE ANALYSIS OF THE 220
222 INJURY MECHANISMS 247
BASKETBALL FREE THROW
EXERCISE/ACTIVITY PRESCRIPTION EXERCISE SPECIFICITY 248
QUALITATIVE ANALYSIS OF CATCHING
EQUIPMENT 250
VIII FUNDAMENTALS OF BIOMECHANICS 251 LAB ACTIVITIES
READINESS 252 1 FINDING BIOMECHANICAL SOURCES L-2
INJURY PREVENTION
SUMMARY 253 2 QUALITATIVE AND QUANTITATIVE
DISCUSSION QUESTIONS
SUGGESTED READING 254 ANALYSIS OF RANGE OF MOTION L-4
WEB LINKS
254 3 FUNCTIONAL ANATOMY? L-6
REFERENCES
255 4 MUSCLE ACTIONS AND THE STRETCH-
APPENDIX A
SHORTENING CYCLE (SSC) L-8
GLOSSARY
257 L-10
APPENDIX B 5A VELOCITY IN SPRINTING
CONVERSION FACTORS 5B ACCURACY OF THROWING
APPENDIX C 283 SPEED MEASUREMENTS L-12
SUGGESTED ANSWERS TO SELECTED 6A TOP GUN KINETICS:
REVIEW QUESTIONS
297 FORCE�MOTION PRINCIPLE L�14
APPENDIX D L-16
6B IMPULSE�MOMENTUM:
RIGHT-ANGLE TRIGONOMETRY FORCE�TIME PRINCIPLE
REVIEW
299 7A ANGULAR KINETICS OF EXERCISE L-18
APPENDIX E
7B CALCULATING CENTER OF GRAVITY L-20
QUALITATIVE ANALYSIS OF USING ANGULAR KINETICS
BIOMECHANICAL PRINCIPLES
305 8 MAGNUS EFFECT IN BASEBALL
INDEX
PITCHING L-22
9 QUALITATIVE ANALYSIS OF L-24
LEAD-UP ACTIVITIES L-26
L-28
307
10 COMPARISON OF SKILLED AND
NOVICE PERFORMANCE
309 11 COMPARISON OF TRAINING
MODES
12 QUALITATIVE ANALYSIS OF L-30
WALKING GAIT
Preface
This second edition of Fundamentals of Lawson & McDermott, 1987; Kim & Pak,
Biomechanics was developed primarily to 2002).
update a well-received text. The unique-
ness of integrating biological and mechani- So why another textbook on the biome-
cal bases in analyzing and improving hu- chanics of human motion? There are plenty
man movement has been expanded with of books that are really anatomy books
more examples, figures, and lab activities. with superficial mechanics, that teach me-
Citations to the latest research and web chanics with sport examples, or are sport
links help students access primary sources. books that use some mechanics to illustrate
Students and instructors will appreciate the technique points. Unfortunately, there are
CD with lab activities, answers to review not many books that truly integrate the bi-
questions, sample questions, and graphics ological and mechanical foundations of hu-
files of the illustrations. man movement and show students how to
apply and integrate biomechanical knowl-
This book is written for students taking edge in improving human movement. This
the introductory biomechanics course in book was written to address these limita-
Kinesiology/HPERD. The book is designed tions in previous biomechanics texts. The
for majors preparing for all kinds of human text presents a clear conceptual under-
movement professions and therefore uses a standing of biomechanics and builds nine
wide variety of movement examples to il- principles for the application of biomechan-
lustrate the application of biomechanics. ics. These nine principles form the applied
While this approach to the application of biomechanics tools kinesiology profession-
biomechanics is critical, it is also important als need. The application of these biome-
that students be introduced to the scientific chanical principles is illustrated in qualita-
support or lack of support for these qualita- tive analysis of a variety of human move-
tive judgments. Throughout the text exten- ments in several contexts for the kinesiolo-
sive citations are provided to support the gy professional: physical education, coach-
principles developed and give students ref- ing, strength and conditioning, and sports
erences for further study. Algebraic level medicine. This qualitative analysis ap-
mathematics is used to teach mechanical proach meets the NASPE Guidelines and
concepts. The focus of the mathematical ex- Standards (Kinesiology Academy, 1992) for
amples is to understand the mechanical an introductory biomechanics course, and
variables and to highlight the relationship clearly shows students how biomechanical
between various biomechanical variables, knowledge must be applied when kinesiol-
rather than to solve quantitative biome- ogy professionals improve human move-
chanical word problems. It is obvious from ment.
research in physics instruction that solving
quantitative word problems does not in- The text is subdivided into four parts:
crease the conceptual understanding of im- Introduction, Biological/Structural Bases,
portant mechanical laws (Elby, 2001; Mechanical Bases, and Applications of
Biomechanics in Qualitative Analysis. Each
ix
X FUNDAMENTALS OF BIOMECHANICS
part opener provides a concise summary of of how the biomechanical principles can be
the importance and content of that section qualitatively applied to improve human
of text. The text builds from familiar ana- movement in a variety of professions. No
tomical knowledge, to new biomechanical other text provides as many or as thorough
principles and their application. guided examples of applying biomechani-
cal principles in actual human movement
This book has several features that are situations. These application chapters also
designed to help students link personal ex- provide discussion questions so that students
perience to biomechanical concepts and and instructors can extend the discussion
that illustrate the application of biome- and debate on professional practice using
chanics principles. First, nine general prin- specific examples.
ciples of biomechanics are proposed and
developed throughout the text. These prin- There are also features that make it easy
ciples are the application link for the bio- for students to follow the material and
mechanical concepts used to improve study for examinations. Extensive use of
movement or reduce injury risk. Some texts graphs, photographs, and illustrations are
have application chapters at the end of the incorporated throughout. Aside from visual
book, but an application approach and ex- appeal, these figures illustrate important
amples are built in throughout Funda- points and relationships between biome-
mentals of Biomechanics. Second, there are chanical variables and performance. The
activity boxes that provide opportunities for book provides an extensive glossary of key
students to see and feel the biomechanical terms and biomechanics research terminolo-
variables discussed. Third, there are practi- gy so that students can read original biome-
cal application boxes that highlight the appli- chanical research. Each chapter provides a
cations of biomechanics in improving summary, extensive citations of important
movement and in treating and preventing biomechanical research, and suggested read-
injury. Fourth, the interdisciplinary issues ings. The chapters in Parts I, II, and III con-
boxes show how biomechanics is integrated clude with review questions for student study
with other sport sciences in addressing hu- and review. The lists of web links offer stu-
man movement problems. Fifth, all chap- dents the internet addresses of significant
ters have associated lab activities (located at websites and professional organizations.
the end of the book, after the index) that use
simple movements and measurements to I hope that you master the fundamen-
explore concepts and principles. These lab tals of biomechanics, integrate biomechan-
activities do not require expensive lab ics into your professional practice, and are
equipment, large blocks of time, or dedicat- challenged to continuously update your
ed lab space. Finally, Part IV (chapters 9 biomechanical toolbox. Some of you will
through 12) provides real-life case studies find advanced study and a career in biome-
chanics exciting opportunities.
Acknowledgments
The author would like to thank the many Knutson for many fine illustrations, and
people who have contributed to the second Aaron Johnson of Springer for his vision to
edition of this book. I am indebted to many make this book happen.
biomechanics colleagues who have shared
their expertise with me, given permission To the ones I truly love--Lois, Josh,
to share their work, and contributed so and Mandy--thanks for being such great
much to students and our profession. I people and for sharing the computer.
would like to thank Tim Oliver for his ex- Finally, I would like to thank God for knit-
pert editing, formatting, design, and art ed- ting all of us so "fearfully and wonderfully
iting of the book, Katherine Hanley- made."
xi
IPART
INTRODUCTION
Kinesiology is the scholarly study of human
movement, and biomechanics is one of the
many academic subdisciplines of kinesiol-
ogy. Biomechanics in kinesiology involves
the precise description of human movement
and the study of the causes of human move-
ment. The study of biomechanics is relevant
to professional practice in many kinesiology
professions. The physical educator or coach
who is teaching movement technique and
the athletic trainer or physical therapist
treating an injury use biomechanics to quali-
tatively analyze movement. The chapters in
part I demonstrate the importance of biome-
chanics in kinesiology and introduce you to
key biomechanical terms and principles that
will be developed throughout the text. The
lab activities associated with part I relate to
finding biomechanical knowledge and iden-
tifying biomechanical principles in action.
1
CHAPTER 1
Introduction to Biomechanics
of Human Movement
Most people are extremely skilled in many WHAT IS BIOMECHANICS?
everyday movements like standing, walk-
ing, or climbing stairs. By the time children Biomechanics has been defined as the study
are two, they are skilled walkers with little of the movement of living things using the sci-
instruction from parents aside from emo- ence of mechanics (Hatze, 1974). Mechanics is
tional encouragement. Unfortunately, mod- a branch of physics that is concerned with
ern living does not require enough move- the description of motion and how forces
ment to prevent several chronic diseases create motion. Forces acting on living
associated with low physical activity (USD- things can create motion, be a healthy stim-
HHS, 1996). Fortunately, many human ulus for growth and development, or over-
movement professions help people to par- load tissues, causing injury. Biomechanics
ticipate in beneficial physical activities. provides conceptual and mathematical
Physical Educators, coaches, athletic train- tools that are necessary for understanding
ers, strength & conditioning coaches, per- how living things move and how kinesiol-
sonal trainers, and physical therapists all ogy professionals might improve move-
help people reap the benefits of physical ac- ment or make movement safer.
tivity. These human movement professions
rely on undergraduate training in kinesiol- Most readers of this book will be ma-
ogy, and typically require coursework in jors in departments of Kinesiology, Human
biomechanics. Kinesiology is the term re- Performance, or HPERD (Health, Physical
ferring to the whole scholarly area of hu- Education, Recreation, and Dance). Kinesi-
man movement study, while biomechanics ology comes from two Greek verbs that
is the study of motion and its causes in liv- translated literally means "the study of
ing things. Biomechanics provides key in- movement." Most American higher educa-
formation on the most effective and safest tion programs in HPERD now use "kinesi-
movement patterns, equipment, and rele- ology" in the title of their department be-
vant exercises to improve human move- cause this term has come to be known as
ment. In a sense, kinesiology professionals the academic area for the study of human
solve human movement problems every movement (Corbin & Eckert, 1990). This
day, and one of their most important tools change in terminology can be confusing be-
is biomechanics. This chapter outlines the cause "kinesiology" is also the title of a
field of biomechanics, why biomechanics is foundational course on applied anatomy
such an important area to the kinesiology that was commonly required for a physical
professional, and where biomechanics in- education degree in the first half of the
formation can be found. twentieth century. This older meaning of
kinesiology persists even today, possibly
3
4 FUNDAMENTALS OF BIOMECHANICS
because biomechanics has only recently many sport and human movement science
(since 1970s) become a recognized special- tools in a kinesiology professional's tool-
ization of scientific study (Atwater, 1980; box. This text is also based on the philoso-
Wilkerson, 1997). phy that your biomechanical tools must be
combined with tools from other kinesiology
This book will use the term kinesiology sciences to most effectively deal with hu-
in the modern sense of the whole academic man movement problems. Figure 1.1a illus-
area of the study of human movement. trates the typical scientific subdisciplines of
Since kinesiology majors are pursuing ca- kinesiology. These typically are the core sci-
reers focused on improving human move- ences all kinesiology majors take in their
ment, you and almost all kinesiology stu- undergraduate preparations. This overview
dents are required to take at least one should not be interpreted to diminish the
course on the biomechanics of human other academic subdisciplines common in
movement. It is a good thing that you are kinesiology departments like sport history,
studying biomechanics. Once your friends sport philosophy, dance, and sport admin-
and family know you are a kinesiology ma- istration/management, just to name a few.
jor, you will invariably be asked questions
like: should I get one of those new rackets, The important point is that knowledge
why does my elbow hurt, or how can I stop from all the subdisciplines must be inte-
my drive from slicing? Does it sometimes grated in professional practice since prob-
seem as if your friends and family have re- lems in human movement are multifaceted,
gressed to that preschool age when every with many interrelated factors. For the
other word out of their mouth is "why"? most part, the human movement problems
What is truly important about this common you face as a kinesiology professional will
experience is that it is a metaphor for the be like those "trick" questions professors
life of a human movement professional. ask on exams: they are complicated by
Professions require formal study of theoret- many factors and tend to defy simple, dual-
ical and specialized knowledge that allows istic (black/white) answers. While the ap-
for the reliable solution to problems. This is plication examples discussed in this text
the traditional meaning of the word "pro- will emphasize biomechanical principles,
fessional," and it is different than its com- readers should bear in mind that this bio-
mon use today. Today people refer to pro- mechanical knowledge should be inte-
fessional athletes or painters because grated with professional experience and the
people earn a living with these jobs, but I other subdisciplines of kinesiology. It is this
believe that kinesiology careers should interdisciplinary approach (Figure 1.1b)
strive to be more like true professions such that is essential to finding the best interven-
as medicine or law. tions to help people more effectively and
safely. Dotson (1980) suggests that true ki-
People need help in improving human nesiology professionals can integrate the
movement and this help requires knowl- many factors that interact to affect move-
edge of "why" and "how" the human body ment, while the layman typically looks at
moves. Since biomechanics gives the kine- things one factor at time. Unfortunately,
siology professional much of the knowl- this interdisciplinary approach to kinesiol-
edge and many of the skills necessary to an- ogy instruction in higher education has
swer these "what works?" and "why?" been elusive (Harris, 1993). Let's look at
questions, biomechanics is an important some examples of human movement prob-
science for solving human movement prob- lems where it is particularly important to
lems. However, biomechanics is but one of
CHAPTER 1: INTRODUCTION TO BIOMECHANICS OF HUMAN MOVEMENT 5
Figure 1.1. (a) The major academic subdisciplines or sciences of kinesiology. (b) Schematic of the integration of all
the sciences in an interdisciplinary approach to solving human movement problems in kinesiology.
integrate biomechanical knowledge into movement can be classified into two main
the qualitative analysis. areas: the improvement of performance
and the reduction or treatment of injury
WHY STUDY BIOMECHANICS? (Figure 1.2).
Scientists from many different areas (e.g., Improving Performance
kinesiology, engineering, physics, biology,
zoology) are interested in biomechanics. Human movement performance can be en-
Why are scholars from so many different hanced many ways. Effective movement
academic backgrounds interested in animal involves anatomical factors, neuromuscu-
movement? Biomechanics is interesting be- lar skills, physiological capacities, and psy-
cause many people marvel at the ability chological/cognitive abilities. Most kinesi-
and beauty in animal movement. Some ology professionals prescribe technique
scholars have purely theoretical or aca- changes and give instructions that allow a
demic interests in discovering the laws person to improve performance. Biome-
and principles that govern animal move- chanics is most useful in improving per-
ment. Within kinesiology, many biomech- formance in sports or activities where tech-
anists have been interested in the applica- nique is the dominant factor rather than
tion of biomechanics to sport and exercise. physical structure or physiological capac-
The applications of biomechanics to human ity. Since biomechanics is essentially the
6 FUNDAMENTALS OF BIOMECHANICS
body arch are performed poorly. The
coach's experience tells him that this athlete
is strong enough to perform this skill, but
they must decide if the gymnast should
concentrate on her takeoff angle or more
back hyperextension in the block. The
coach uses his knowledge of biomechanics
to help in the qualitative analysis of this sit-
uation. Since the coach knows that a better
arch affects the force the gymnast creates
against the mat and affects the angle of
takeoff of the gymnast, he decides to help
the gymnast work on her "arch" following
the round off.
Biomechanics research on sports tech-
niques sometimes tends to lag behind the
changes that are naturally occurring in
sports. Athletes and coaches experiment
with new techniques all the time. Students
of biomechanics may be surprised to find
that there are often limited biomechanical
Figure 1.2. The two major applications of biomechan-
ics are to improve human movement and the treat-
ment or prevention of injury.
science of movement technique, biome- Figure 1.3. Biomechanics principles must be inte-
chanics is the main contributor to one of the grated with other kinesiology sciences to solve human
most important skills of kinesiology profes- movement problems, like in the qualitative analysis a
sionals: the qualitative analysis of human round off and back handspring.
movement (Knudson & Morrison, 2002).
Imagine a coach is working with a
gymnast who is having problems with her
back handspring (Figure 1.3). The coach ob-
serves several attempts and judges that the
angle of takeoff from the round off and
CHAPTER 1: INTRODUCTION TO BIOMECHANICS OF HUMAN MOVEMENT 7
studies on many techniques in many popu- ing designs. When these changes are
lar sports. The vast number of techniques, integrated with information about the
their variations, and their high rates of human performer, we can say the improve-
change and innovation tend to outdistance ments in equipment were based on biome-
biomechanics research resources. Sport bio- chanics. Engineers interested in sports
mechanics research also lags behind the equipment often belong to the Intern-
coaches and athletes because scientific re- ational Sports Engineering Association
search takes considerable time to conduct (http://www.sportsengineering.org/) and
and report, and there is a lack of funding publish research in ISEA proceedings
for this important research. There is less (Subic & Haake, 2000) or the Sports Engi-
funding for biomechanical studies aimed at neering journal. Research on all kinds of
improving performance compared to stud- equipment is conducted in biomechanics
ies focused on preventing and treating in- labs at most major sporting goods manu-
juries. Students looking for biomechanical facturers. Unfortunately, much of the re-
research on improving sports technique of- sults of these studies are closely guarded
ten will have fewer sources than students trade secrets, and it is difficult for the
researching the biomechanics of injury. layperson to determine if marketing claims
for "improvements" in equipment design
While technique is always relevant in are real biomechanical innovations or just
human movement, in some activities the creative marketing.
psychological, anatomical, or physiological
factors are more strongly related to success. There are many examples of how ap-
Running is a good example of this kind of plying biomechanics in changing equip-
movement. There is a considerable amount ment designs has improved sports per-
of research on the biomechanics of running formance. When improved javelin designs
so coaches can fine tune a runner's tech- in the early 1980s resulted in longer throws
nique to match the profile of elite runners that endangered other athletes and specta-
(Cavanagh, Andrew, Kram, Rogers, San- tors, redesigns in the weight distribution of
derson, & Hennig, 1985; Buckalew, Barlow, the "new rules" javelin again shortened
Fischer, & Richards, 1985; Williams, Ca- throws to safer distances (Hubbard & Al-
vanagh, & Ziff, 1987). While these tech- aways, 1987). Biomechanics researchers (El-
nique adjustments make small improve- liott, 1981; Ward & Groppel, 1980) were
ments in performance, most of running some of the first to call for smaller tennis
performance is related to physiological rackets that more closely matched the mus-
abilities and their training. Studies that pro- cular strength of young players (Figure 1.4).
vide technique changes in running based Chapter 8 will discuss how changes in
on biomechanical measurements have sports equipment are used to change fluid
found minimal effects on running economy forces and improve performance.
(Cavanagh, 1990; Lake & Cavanagh, 1996;
Messier & Cirillo, 1989). This suggests that While breaking world records using
track coaches can use biomechanics to re- new equipment is exciting, not all changes
fine running technique, but they should in equipment are welcomed with open
only expect small changes in performance arms by sport governing bodies. Some
from these modifications. equipment changes are so drastic they
change the very nature of the game and are
Human performance can also be en- quickly outlawed by the rules committee of
hanced by improvements in the design of the sport. One biomechanist developed a
equipment. Many of these improvements way to measure the stiffness of basketball
are related to new materials and engineer- goals, hoping to improve the consistency of
8 FUNDAMENTALS OF BIOMECHANICS
Figure 1.4. The design of sports equipment must be of the engineers than athletes (Bjerklie,
appropriate for an athlete, so rackets for children are 1993).
shorter and lighter than adult rackets. Photo used with
permission from Getty Images. Another way biomechanics research
improves performance is advances in exer-
cise and conditioning programs. Bio-
mechanical studies of exercise movements
and training devices serve to determine the
most effective training to improve perform-
ance (Figure 1.5). Biomechanical research
on exercises is often compared to research
on the sport or activity that is the focus of
training. Strength and conditioning profes-
sionals can better apply the principle of
specificity when biomechanical research is
used in the development of exercise pro-
grams. Computer-controlled exercise and
testing machines are another example of
how biomechanics contributes to strength
and conditioning (Ariel, 1983). In the next
section the application of biomechanics in
the medical areas of orthotics and prosthet-
ics will be mentioned in relation to prevent-
ing injury, but many prosthetics are now
being designed to improve the performance
of disabled athletes.
their response but found considerable re- Figure 1.5. A computerized testing and exercise dy-
sistance from basketball folks who liked namometer by Biodex. The speed, muscle actions (iso-
their unique home court advantages. An- metric, concentric, eccentric), and pattern of loading
other biomechanist recently developed a (isokinetic, isotonic) can be selected. Image courtesy of
new "klap" speed skate that increased the Biodex Medical Systems.
time and range of motion of each push off
the ice, dramatically improving times and
breaking world records (de Koning, Hou-
dijk, de Groot, & Bobbert, 2000). This gave
quite an advantage to the country where
these skates were developed, and there was
controversy over the amount of time other
skaters were able to practice with the new
skates before competition. These dramatic
equipment improvements in many sports
have some people worried that winning
Olympic medals may be more in the hands
CHAPTER 1: INTRODUCTION TO BIOMECHANICS OF HUMAN MOVEMENT 9
Preventing and Treating Injury amputation, prosthetics or artificial limbs
can be designed to match the mechanical
Movement safety, or injury prevention/ properties of the missing limb (Klute
treatment, is another primary area where Kallfelz, & Czerniecki, 2001). Preventing
biomechanics can be applied. Sports medi- acute injuries is also another area of biome-
cine professionals have traditionally stud- chanics research. Forensic biomechanics in-
ied injury data to try to determine the volves reconstructing the likely causes of
potential causes of disease or injury (epi- injury from accident measurements and
demiology). Biomechanical research is a witness testimony.
powerful ally in the sports medicine quest
to prevent and treat injury. Biomechanical Biomechanics helps the physical thera-
studies help prevent injuries by providing pist prescribe rehabilitative exercises, assis-
information on the mechanical properties tive devices, or orthotics. Orthotics are
of tissues, mechanical loadings during support objects/braces that correct defor-
movement, and preventative or rehabilita- mities or joint positioning, while assistive
tive therapies. Biomechanical studies pro- devices are large tools to help patient func-
vide important data to confirm potential in- tion like canes or walkers. Qualitative
jury mechanisms hypothesized by sports analysis of gait (walking) also helps the
medicine physicians and epidemiological therapist decide whether sufficient muscu-
studies. The increased participation of girls lar strength and control have been regained
and women in sports has made it clear that in order to permit safe or cosmetically nor-
females are at a higher risk for anterior cru- mal walking (Figure 1.6). An athletic trainer
ciate ligament (ACL) injuries than males might observe the walking pattern for
due to several biomechanical factors (Bo- signs of pain and/or limited range of mo-
den, Griffin, & Garrett, 2000). Continued tion in an athlete undergoing long-term
biomechanical and sports medicine studies conditioning for future return to the field.
may help unravel the mystery of this high An athletic coach might use a similar quali-
risk and develop prevention strategies (see
Chapter 12). Figure 1.6. Qualitative analysis of gait (walking) is of
importance in physical therapy and the treatment of
Engineers and occupational therapists many musculoskeletal conditions.
use biomechanics to design work tasks and
assistive equipment to prevent overuse in-
juries related to specific jobs. Combining
biomechanics with other sport sciences has
aided in the design of shoes for specific
sports (Segesser & Pforringer, 1989), espe-
cially running shoes (Frederick, 1986; Nigg,
1986). Since the 1980s the design and engi-
neering of most sports shoes has included
research in company biomechanics labs.
The biomechanical study of auto accidents
has resulted in measures of the severity of
head injuries, which has been applied in
biomechanical testing, and in design of
many kinds of helmets to prevent head in-
jury (Calvano & Berger, 1979; Norman,
1983; Torg, 1992). When accidents result in
10 FUNDAMENTALS OF BIOMECHANICS
tative analysis of the warm-up activities of Figure 1.7. Biomechanical measurements and soft-
the same athlete several weeks later to ware can be used to make accurate animations of hu-
judge their readiness for practice or compe- man motion that can be used for technique improve-
tition. Many biomechanists work in hospi- ment, cinema special effects, and computer games.
tals providing quantitative assessments of Drawing based on image provided by Vicon Motion
gait function to document the effectiveness Systems.
of therapy. The North American group in-
terested in these quantitative assessments that computer game animations have the
for medical purposes is the Gait and Clini- look of truly human movement, but with
cal Movement Analysis Society (GCMAS) the superhuman speed that makes games
at http://www.gcmas.net/cms/index.php. exciting (Figure 1.7). Some people use bio-
Good sources for the clinical and biome- mechanics to perform forensic examina-
chanical aspects of gait are Kirtley (2006), tions. This reconstruction of events from
Perry (1992), Whittle (1996), and the clini- physical measurements at the scene is com-
cal gait analysis website: http://guardian. bined with medical and other evidence to
curtin.edu.au/cga/. determine the likely cause of many kinds of
accidents.
Dramatic increases in computer mem-
ory and power have opened up new areas
of application for biomechanists. Many of
these areas are related to treating and pre-
venting human injury. Biomechanical stud-
ies are able to evaluate strategies for pre-
venting falls and fractures in the elderly
(Robinovitch, Hsiao, Sandler, Cortez, Liu, &
Paiement, 2000). Biomechanical computer
models can be used to simulate the effect of
various orthopaedic surgeries (Delp, Loan,
Hoy, Zajac, & Rosen, 1990) or to educate
with computer animation. Some biomech-
anists have developed software used to
adapt human movement kinematic data so
Application
A variety of professions are interested in using biomechanics to modify human movement.A person that
fabricates prosthetics (artificial limbs) would use biomechanics to understand the normal functioning of
joints, the loadings the prosthetic must withstand, and how the prosthetic can be safely attached to the
person. List possible questions biomechanics could answer for a(n):
Athletic Coach?
Orthopaedic Surgeon?
Physical Educator?
Physical Therapist?
Athletic Trainer?
Strength & Conditioning Professional?
Occupational Fitness Consultant?
You? What question about human movement technique are you curious about?
---
[Cuối tài liệu]
L-26 FUNDAMENTALS OF BIOMECHANICS
LAB ACTIVITY 10
COMPARISON OF SKILLED AND NOVICE PERFORMANCE
Coaching strives to maximize the performance of an athlete or team in competition. A key
ingredient of athletic success is motor skill. Most aspects of skill are related to the biome-
chanical principles of human movement. A good way to practice the qualitative analysis of
sport skills is to compare the application of biomechanical principles of a novice and those
of a skilled performer. The purpose of this lab is to compare the application of biomechan-
ical principles in a skilled performer and a novice performer in a common sport skill.
BACKGROUND READING
Chapter 10 herein: "Applying Biomechanics in Coaching"
Hay, J. G. (1993). The biomechanics of sports techniques (4th. ed.). Englewood Cliffs, NJ:
Prentice-Hall.
Knudson, D. V., & Morrison, C. S. (2002). Qualitative analysis of human movement (2nd ed.).
Champaign, IL: Human Kinetics.
TASKS
1. Select a sport skill where a novice and a skilled performer can be found from students in
the lab.
2. Select two volunteers (one novice and one skilled) to perform the skill.
3. Videotape several repetitions of the skill from several angles
4. Observe and evaluate performance of the biomechanical principles in each movement us-
ing videotape replay.
5. Answer the questions.
Copyright � 2007 Springer Science+Business Media, LLC. All rights reserved.
LAB ACTIVITIES L-27
LAB ACTIVITY 10 NAME _____________________________
COMPARISON OF SKILLED AND NOVICE PERFORMANCE
1. What are the biomechanical principles most relevant to the sport skill of interest?
2. What biomechanical principles are strengths and weaknesses for the novice performer?
3. What biomechanical principles are strengths and weaknesses for the skilled performer?
4. What intervention would you recommend for the novice performer and why?
5. What intervention would you recommend for the skilled performer and why?
Copyright � 2007 Springer Science+Business Media, LLC. All rights reserved.
L-28 FUNDAMENTALS OF BIOMECHANICS
LAB ACTIVITY 11
COMPARISON OF TRAINING MODES
Strength and conditioning coaches prescribe exercises to improve performance based on the
Principle of Specificity. This is often called the "SAID" principle: Specific Adaptation to
Imposed Demands. There are a variety of free-weight, elastic, and mechanical resistances
that coaches can prescribe to train the neuromuscular system. Qualitative analysis of exer-
cise technique based on biomechanical principles can help a strength coach make two im-
portant evaluations: is the exercise technique safe and is it sport-specific? This lab will fo-
cus on the latter. The purpose of this lab is to compare the specificity of exercise technique
in training for a sport skill.
BACKGROUND READING
Chapter 11 herein: "Applying Biomechanics in Strength and Conditioning"
Knudson, D. V., & Morrison, C. S. (2002). Qualitative analysis of human movement (2nd ed.).
Champaign, IL: Human Kinetics.
TASKS
1. Select a sport skill of interest.
2. Select three exercises that will train the main agonists for the propulsive phase of the skill.
Be sure to select an elastic resistance, inertial resistance (free weight), and an exercise ma-
chine. Strive to make the resistances about equal in these exercises.
3. Select a volunteer to perform the exercises.
4. Videotape several repetitions of the exercises perpendicular to the primary plane of
movement.
5. Observe and evaluate the performance of the biomechanical principles in each exercise
using videotape replay.
6. Answer the questions.
Copyright � 2007 Springer Science+Business Media, LLC. All rights reserved.
LAB ACTIVITY 11 LAB ACTIVITIES L-29
NAME _____________________________
COMPARISON OF TRAINING MODES
1. What are the biomechanical principles most relevant to the sport skill of interest?
2. What was the first exercise? What biomechanical principles of this exercise are similar to
the sport skill?
3. What was the second exercise? What biomechanical principles of this exercise are similar
to the sport skill?
4. What was the third exercise? What biomechanical principles of this exercise are similar to
the sport skill?
5. Which exercise was most sport-specific? Why? (Be sure to explain based on the impor-
tance of certain biomechanical principles in terms of performance in the sport.)
Copyright � 2007 Springer Science+Business Media, LLC. All rights reserved.
L-30 FUNDAMENTALS OF BIOMECHANICS
LAB ACTIVITY 12
QUALITATIVE ANALYSIS OF WALKING GAIT
Sports medicine professionals qualitatively analyze movement to find clues to injury and to
monitor recovery from injury. Walking is a well-learned movement that athletic trainers,
physical therapists, and physicians all qualitatively analyze to evaluate lower-extremity
function. There is a variety of qualitative and quantitative systems of gait analysis. This lab
will focus on the qualitative analysis of two walking gaits based on biomechanical princi-
ples. Professionals qualitatively analyzing gait must remember that quantitative biome-
chanical analyses are needed in order to correctly estimate the loads in musculoskeletal
structures, so assumptions about muscle actions in gait from body positioning alone are un-
wise (Herbert et al., 1993).
BACKGROUND READING
Chapter 12 herein: "Applying Biomechanics in Sports Medicine and Rehabilitation"
Herbert, R., Moore, S., Moseley, A., Schurr, K., & Wales, A. (1993). Making inferences about
muscles forces from clinical observations. Australian Journal of Physiotherapy, 39,
195�202.
Knudson, D. V., & Morrison, C. S. (2002). Qualitative analysis of human movement (2nd ed.).
Champaign, IL: Human Kinetics.
Whittle, M. (1996). Gait analysis: An introduction (2nd ed.). Oxford: Butterworth-Heinemann.
TASKS
1. Select a volunteer to perform the walking trials.
2. Have the volunteer walk in three conditions: their natural gait, as fast as they comfort-
ably can, and simulating an injury. Injury can be easily simulated by restricting joint mo-
tion with athletic tape or a brace. Antalgic (painful) gait can be simulated by placing a
small stone in a shoe.
3. Videotape several cycles of each waking gait.
4. Observe and evaluate performance related to the biomechanical principles in each gait
using videotape replay.
5. Answer the questions.
Copyright � 2007 Springer Science+Business Media, LLC. All rights reserved.
LAB ACTIVITIES L-31
LAB ACTIVITY 12 NAME _____________________________
QUALITATIVE ANALYSIS OF WALKING GAIT
1. What biomechanical principles are most evident in natural walking gait?
2. What biomechanical principles increased or decreased in importance relative to normal
gait, during fast gait?
3. What injury did you simulate? What biomechanical principles increased or decreased in
importance relative to normal gait, during injured gait?
4. What musculoskeletal structures are affected in your simulated injury? Hypothesize the
likely changes in muscular actions and kinematics because of this injury and note where
you might find biomechanical literature to confirm your diagnosis.
Copyright � 2007 Springer Science+Business Media, LLC. All rights reserved.