Essentials of Strength and Conditioning 4th Edition PDF

Essentials of Strength Training and Conditioning Fourth Edition G. Gregory Haff, PhD, CSCS,*D, FNSCA Edith Cowan University, Western Australia N. Travis Triplett, PhD, CSCS,*D, FNSCA Appalachian State University, Boone, NC Editors H...

Essentials of Strength Training and Conditioning Fourth Edition G. Gregory Haff, PhD, CSCS,*D, FNSCA Edith Cowan University, Western Australia N. Travis Triplett, PhD, CSCS,*D, FNSCA Appalachian State University, Boone, NC Editors Human Kinetics  Library of Congress Cataloging-in-Publication Data Essentials of strength training and conditioning / National Strength and Conditioning Association ; G. Gregory Haff, N. Travis Triplett, editors. -- Fourth edition. p. ; cm. Includes bibliographical references and index. I. Haff, Greg, editor. II. Triplett, N. Travis, 1964- , editor. III. National Strength & Conditioning Association (U.S.), issuing body. [DNLM: 1. Physical Education and Training--methods. 2. Athletic Performance--physiology. 3. Physical Conditioning, Human--physiology. 4. Physical Fitness--physiology. 5. Resistance Training--methods. QT 255] GV711.5 613.7'1--dc23 2014047045 ISBN: 978-1-4925-0162-6 Copyright © 2016, 2008, 2000, 1994 by the National Strength and Conditioning Association All rights reserved. Except for use in a review, the reproduction or utilization of this work in any form or by any electronic, mechanical, or other means, now known or hereafter invented, including xerography, photocopying, and recording, and in any information storage and retrieval system, is forbidden without the written permission of the publisher. Notice: Permission to reproduce the following material is granted to individuals and agencies who have purchased Essentials of Strength Training and Conditioning, Fourth Edition: pp. 636, 637-639, 645. The reproduction of other parts of this book is expressly forbidden by the above copyright notice. Persons or agencies who have not purchased Essentials of Strength Training and Conditioning, Fourth Edition, may not reproduce any material. Permission notices for material reprinted in this book from other sources can be found on pages xv-xvi. The web addresses cited in this text were current as of April 2015, unless otherwise noted. Acquisitions Editor: Roger W. Earle; Developmental Editor: Christine M. Drews; Managing Editor: Karla Walsh; Copy- editor: Joyce Sexton; Indexer: Susan Danzi Hernandez; Permissions Manager: Dalene Reeder; Graphic Designer: Nancy Rasmus; Cover Designer: Keith Blomberg; Photographer: Neil Bernstein, unless otherwise noted; all photos © Human Kinetics, unless otherwise noted; Photo Asset Manager: Laura Fitch; Visual Production Assistant: Joyce Brumfield; Photo Production Manager: Jason Allen; Art Manager: Kelly Hendren; Associate Art Manager: Alan L. Wilborn; Art Style Development: Joanne Brummett; Illustrations: © Human Kinetics, unless otherwise noted; Printer: RR Donnelley We thank The Fitness Center in Champaign, Illinois, and the National Strength and Conditioning Association in Colorado Springs, Colorado, for assistance in providing the locations for the photo shoot for this book. The video contents of this product are licensed for private home use and traditional, face-to-face classroom instruction only. For public performance licensing, please contact a sales representative at www.HumanKinetics.com/SalesRepresentatives. Printed in the United States of America 10 9 8 7 6 5 4 3 2 1 The paper in this book was manufactured using responsible forestry methods. Human Kinetics Website: www.HumanKinetics.com United States: Human Kinetics Australia: Human Kinetics P.O. Box 5076 57A Price Avenue Champaign, IL 61825-5076 Lower Mitcham, South Australia 5062 800-747-4457 08 8372 0999 e-mail: [email protected] e-mail: [email protected] Canada: Human Kinetics New Zealand: Human Kinetics 475 Devonshire Road Unit 100 P.O. Box 80 Windsor, ON N8Y 2L5 Mitcham Shopping Centre, South Australia 5062 800-465-7301 (in Canada only) 0800 222 062 e-mail: [email protected] e-mail: [email protected] Europe: Human Kinetics 107 Bradford Road Stanningley Leeds LS28 6AT, United Kingdom +44 (0) 113 255 5665 e-mail: [email protected] E6372 CONTENTS Preface vii Accessing the Lab Activities xi Acknowledgments xiii Credits xv CHAPTER 1 Structure and Function of Body Systems 1 N. Travis Triplett, PhD Musculoskeletal System 2 Neuromuscular System 8 Cardiovascular System 12 Respiratory System 15 Conclusion 17 Learning Aids 17 CHAPTER 2 Biomechanics of Resistance Exercise 19 Jeffrey M. McBride, PhD Skeletal Musculature 20 Anatomical Planes and Major Body Movements 25 Human Strength and Power 25 Sources of Resistance to Muscle Contraction 33 Joint Biomechanics: Concerns in Resistance Training 37 Conclusion 40 Learning Aids 41 CHAPTER 3 Bioenergetics of Exercise and Training 43 Trent J. Herda, PhD, and Joel T. Cramer, PhD Essential Terminology 44 Biological Energy Systems 44 Substrate Depletion and Repletion 55 Bioenergetic Limiting Factors in Exercise Performance 56 Oxygen Uptake and the Aerobic and Anaerobic Contributions to Exercise 57 Metabolic Specificity of Training 59 Conclusion 61 Learning Aids 62 CHAPTER 4 Endocrine Responses to Resistance Exercise 65 William J. Kraemer, PhD, Jakob L. Vingren, PhD, and Barry A. Spiering, PhD Synthesis, Storage, and Secretion of Hormones 66 Muscle as the Target for Hormone Interactions 69 Role of Receptors in Mediating Hormonal Changes 69 Categories of Hormones 70 Heavy Resistance Exercise and Hormonal Increases 72 Mechanisms of Hormonal Interactions 72 Hormonal Changes in Peripheral Blood 73 Adaptations in the Endocrine System 73 Primary Anabolic Hormones 74 Adrenal Hormones 82 Other Hormonal Considerations 84 Conclusion 85 Learning Aids 86 iii iv Contents Chapter 5 Adaptations to Anaerobic Training Programs 87 Duncan French, PhD Neural Adaptations 88 Muscular Adaptations 93 Connective Tissue Adaptations 97 Endocrine Responses and Adaptations to Anaerobic Training 102 Cardiovascular and Respiratory Responses to Anaerobic Exercise 103 Compatibility of Aerobic and Anaerobic Modes of Training 105 Overtraining 107 Detraining 110 Conclusion 111 Learning Aids 112 Chapter 6 Adaptations to Aerobic Endurance Training Programs 115 Ann Swank, PhD, and Carwyn Sharp, PhD Acute Responses to Aerobic Exercise 116 Chronic Adaptations to Aerobic Exercise 120 Adaptations to Aerobic Endurance Training 124 External and Individual Factors Influencing Adaptations to Aerobic Endurance Training 124 Overtraining: Definition, Prevalence, Diagnosis, and Potential Markers 129 Conclusion 132 Learning Aids 133 Chapter 7 Age- and Sex-Related Differences and Their Implications for Resistance Exercise 135 Rhodri S. Lloyd, PhD, and Avery D. Faigenbaum, EdD Children 136 Female Athletes 144 Older Adults 148 Conclusion 153 Learning Aids 154 Chapter 8 Psychology of Athletic Preparation and Performance 155 Traci A. Statler, PhD, and Andrea M. DuBois, MS Role of Sport Psychology 156 Ideal Performance State 156 Energy Management: Arousal, Anxiety, and Stress 157 Influence of Arousal and Anxiety on Performance 158 Motivation 161 Attention and Focus 163 Psychological Techniques for Improved Performance 164 Enhancing Motor Skill Acquisition and Learning 169 Conclusion 172 Learning Aids 173 Chapter 9 Basic Nutrition Factors in Health 175 Marie Spano, MS, RD Role of Sports Nutrition Professionals 176 Standard Nutrition Guidelines 178 Macronutrients 181 Vitamins 190 Minerals 193 Fluid and Electrolytes 196 Conclusion 199 Learning Aids 200 Chapter 10 Nutrition Strategies for Maximizing Performance 201 Marie Spano, MS, RD Precompetition, During-Event, and Postcompetition Nutrition 202 Nutrition Strategies for Altering Body Composition 216 Feeding and Eating Disorders 221 Conclusion 224 Learning Aids 224 Chapter 11 Performance-Enhancing Substances and Methods 225 Bill Campbell, PhD Types of Performance-Enhancing Substances 226 Hormones 228 Dietary Supplements 237 Conclusion 247 Learning Aids 248  Contents v Chapter 12 Principles of Test Selection and Administration 249 Michael McGuigan, PhD Reasons for Testing 250 Testing Terminology 250 Evaluation of Test Quality 250 Test Selection 253 Test Administration 254 Conclusion 257 Learning Aids 258 Chapter 13 Administration, Scoring, and Interpretation of Selected Tests 259 Michael McGuigan, PhD Measuring Parameters of Athletic Performance 260 Selected Test Protocols and Scoring Data 264 Statistical Evaluation of Test Data 291 Conclusion 293 Learning Aids 294 Chapter 14 Warm-Up and Flexibility Training 317 Ian Jeffreys, PhD Warm-Up 318 Flexibility 320 Types of Stretching 323 Conclusion 328 Static Stretching Techniques 329 Dynamic Stretching Techniques 341 Learning Aids 350 Chapter 15 Exercise Technique for Free Weight and Machine Training 351 Scott Caulfield, BS, and Douglas Berninger, MEd Fundamentals of Exercise Technique 352 Spotting Free Weight Exercises 354 Conclusion 357 Resistance Training Exercises 358 Learning Aids 408 Chapter 16 Exercise Technique for Alternative Modes and Nontraditional Implement Training 409 G. Gregory Haff, PhD, Douglas Berninger, MEd, and Scott Caulfield, BS General Guidelines 410 Bodyweight Training Methods 410 Core Stability and Balance Training Methods 411 Variable-Resistance Training Methods 413 Nontraditional Implement Training Methods 417 Unilateral Training 421 Conclusion 421 Modes and Nontraditional Exercises 422 Learning Aids 438 Chapter 17 Program Design for Resistance Training 439 Jeremy M. Sheppard, PhD, and N. Travis Triplett, PhD Principles of Anaerobic Exercise Prescription 440 Step 1: Needs Analysis 441 Step 2: Exercise Selection 443 Step 3: Training Frequency 447 Step 4: Exercise Order 448 Step 5: Training Load and Repetitions 451 Step 6: Volume 462 Step 7: Rest Periods 465 Conclusion 467 Learning Aids 469 Chapter 18 Program Design and Technique for Plyometric Training 471 David H. Potach, PT, and Donald A. Chu, PhD, PT Plyometric Mechanics and Physiology 472 Program Design 475 Age Considerations 478 Plyometrics and Other Forms of Exercise 480 Safety Considerations 481 Conclusion 482 Plyometric Drills 483 Learning Aids 520 vi Contents Chapter 19 Program Design and Technique for Speed and Agility Training 521 Brad H. DeWeese, EdD, and Sophia Nimphius, PhD Speed and Agility Mechanics 522 Neurophysiological Basis for Speed 525 Running Speed 527 Agility Performance and Change-of-Direction Ability 533 Methods of Developing Speed 536 Methods of Developing Agility 538 Program Design 539 Speed Development Strategies 541 Agility Development Strategies 545 Conclusion 547 Speed and Agility Drills 548 Learning Aids 557 Chapter 20 Program Design and Technique for Aerobic Endurance Training 559 Benjamin H. Reuter, PhD, and J. Jay Dawes, PhD Factors Related to Aerobic Endurance Performance 560 Designing an Aerobic Endurance Program 561 Types of Aerobic Endurance Training Programs 567 Application of Program Design to Training Seasons 570 Special Issues Related to Aerobic Endurance Training 571 Conclusion 573 Aerobic Endurance Training Exercises 574 Learning Aids 581 Chapter 21 Periodization 583 G. Gregory Haff, PhD Central Concepts Related to Periodization 584 Periodization Hierarchy 587 Periodization Periods 588 Applying Sport Seasons to the Periodization Periods 592 Undulating Versus Linear Periodization Models 593 Example of an Annual Training Plan 593 Conclusion 595 Learning Aids 604 Chapter 22 Rehabilitation and Reconditioning 605 David H. Potach, PT, and Terry L. Grindstaff, PhD, PT, ATC Sports Medicine Team 606 Types of Injury 608 Tissue Healing 610 Goals of Rehabilitation and Reconditioning 611 Program Design 616 Reducing Risk of Injury and Reinjury 618 Conclusion 620 Learning Aids 621 Chapter 23 Facility Design, Layout, and Organization 623 Andrea Hudy, MA General Aspects of New Facility Design 624 Existing Strength and Conditioning Facilities 625 Assessing Athletic Program Needs 625 Designing the Strength and Conditioning Facility 627 Arranging Equipment in the Strength and Conditioning Facility 628 Maintaining and Cleaning Surfaces and Equipment 630 Conclusion 631 Learning Aids 633 Chapter 24 Facility Policies, Procedures, and Legal Issues 641 Traci Statler, PhD, and Victor Brown, MS Mission Statement and Program Goals 642 Program Objectives 642 Strength and Conditioning Performance Team 643 Legal and Ethical Issues 647 Staff Policies and Activities 651 Facility Administration 653 Emergency Planning and Response 653 Conclusion 655 Learning Aids 656 Answers to Study Questions 657 References 659 Index 721 About the Editors 731 Contributors 733 Contributors to Previous Editions 735 PREFACE In 1994, the first edition of Essentials of Strength Train- Updates to the Fourth Edition ing and Conditioning was published. After a second edition (in 2000) and sales of over 100,000 books, an This fourth edition expands on the earlier editions and expanded and updated third edition was published in applies the most current research and information in 2008. This newest edition continues the tradition as the a logical format that reaffirms Essentials of Strength most comprehensive reference available for strength Training and Conditioning as the most prominent and conditioning professionals. In this text, 30 expert resource for students preparing for careers in strength contributors further explore the scientific principles, and conditioning and for sport science professionals concepts, and theories of strength training and condi- involved in training athletes. The primary enhancements tioning and their applications to athletic performance. are as follows: The first edition grew out of an awareness that there was not a book about strength training and condition- Online videos featuring 21 resistance training ing that captured the views of leading professionals in exercises demonstrate proper exercise form for anatomy, biochemistry, biomechanics, endocrinology, classroom and practical use. nutrition, exercise physiology, psychology, and the Updated research—specifically in the areas of other sciences and that related the principles from these high-intensity interval training, overtraining, disciplines to the design of safe and effective training agility and change of direction, nutrition for programs. Also, the lack of relevant and well-conducted health and performance, and periodization—helps research studies had hindered earlier efforts to create an readers better understand these popular trends in all-inclusive resource. Once it was finally developed, the industry. Essentials of Strength Training and Conditioning quickly A new chapter with instructions and photos pres- became the definitive textbook on the subject. ents techniques for exercises using alternative The second edition, released six years later, was modes and nontraditional implements. more than a simple freshening of the content; it was an Ten additional tests, including tests for maximum overhaul of the scope and application of the first edi- strength, power, and aerobic capacity, along with tion. Throughout the text and in the additional 100-plus new flexibility exercises, resistance training exer- pages, the chapter contributors used updated, relevant, cises, plyometric exercises, and speed and agility and conclusive research and concepts to turn scientific drills, help professionals design programs that information into information on performance. Many reflect current guidelines. learning tools were added, such as chapter objectives, key points, application boxes, and sample resistance These enhancements, plus an expanded ancillary training programs for three different sports. These package for instructors including a new, robust collec- enhancements, plus the addition of a full-color interior tion of more than 60 instructor videos demonstrating and hundreds of color photographs, made the second resistance training, plyometric exercises, and alter- edition truly exceptional. native mode exercises, brings practical content to the The third edition, released eight years after the second classroom. Working along with the instructor guide and edition, offered restructured chapters and expansions presentation package, a test package has been added to of other chapters complete with new photographs and assist instructors in evaluating students’ understanding updated terminology. In addition, the artwork was mod- of key concepts. ernized and instructor and student resources were created Each chapter begins with objectives and includes key to help keep this text the primary resource for the study points to guide the reader along the way. Key terms are and instruction of strength and conditioning. boldfaced and listed at the end of the chapter. Chapters vii viii Preface include sidebars that apply the content, and later chap- Presentation Package and Image Bank. This ters include sample resistance training programs for comprehensive resource, delivered in Microsoft three different sports. Detailed instructions and photos PowerPoint, offers instructors a presentation are provided for testing, stretching, resistance training, package containing over 1,300 slides to help aug- alternative modes, plyometrics, agility training, and ment lectures and class discussions. In addition aerobic endurance exercise. Finally, chapters end with to outlines and key points, the resource contains multiple-choice study questions, with an answer key at more than 600 figures, tables, and photos from the the end of the book. textbook, which can be used as an image bank by instructors who need to customize their presen- tations. Easy-to-follow instructions help guide Instructor Resources instructors on how to reuse the images within In addition to the updated content, this edition includes their own PowerPoint templates. newly created instructor resources: Test Package. The test package includes a bank of 240 multiple-choice questions, from which Instructor Video. The instructor video includes instructors can make their own tests and quizzes. video of correct technique for 61 resistance Instructors can download Respondus or RTF files training, alternative, and plyometric exercises. or files formatted for use in a learning manage- These can be used for demonstration, lecture, ment system. and discussion. Instructor Guide. The instructor guide contains a These instructor resources can be found at www.Human course description, a sample semester schedule, Kinetics.com/EssentialsOfStrengthTrainingAnd chapter objectives, chapter outlines, key terms Conditioning. with definitions, and application questions with Video available online answers. Chest 15.15 FLAT DU 8 Essentials of Strength Training and Conditioning MBBELL FLY (and Incline Va This exercise can also be per riation) double helix. The myosin crossbridge now attaches much myosin, and resetting of the myosin head position—is bench. If usin formed on an g the incline var incline ing iatio Keep the dum more rapidly to the actin filament, allowing force to be repeated over and over again throughout the muscle the dumbbells over the hea n, begin by position- bbell handles parallel to eac ove d and face inst as the elbows produced as the actin filaments are pulled toward the fiber. This occurs as long as calcium is available in the r the chest. ead of move downw ard. h other Keep the wri center of the sarcomere (1). It is important to understand myofibril, ATP is available to assist in uncoupling Sta therting Positio sts stiff and the n: Athlete slightly flexed elbows held in a that the amount of force produced by a muscle at any myosin from the actin, and sufficient active myosin Grasp two dum position. bbells using a Keep the han instant in time is directly related to the number of myosin ATPase is available for catalyzing the breakdown of ATP. Lie in closed, neutral ds, wrists, fore arms, elbows, a supine pos grip. arms, and sho upper crossbridges bound to actin filaments cross-sectionally ition on ulders in the Relaxation Phase Relaxation occurs when the stim- point body contact positio a bench in the five- Maintain the same vertical plane. at that instant in time (1). Signal the n. five-point bod y contact pos ulation of the motor nerve stops. Calcium is pumped spotter for ass Downward Mo ition. Key points ▶ The number of crossbridges that are formed Press the dum ista back into the sarcoplasmic reticulum, which prevents thedumbbells into the startin nce in moving the g position. Keep the han vement Pha se: Spotter link between the actin and myosin filaments. Relaxation bbells in uni ds near—but athlete’s forearm not touching— between actin and myosin at any instant is brought about by the return of the actin and myosinbow position above the son to an extended-el- s near the wri the in time dictates the force production of a Slightly flex chest. bells descend. sts as the dum filaments to their unbound state. the elbow b- muscle. the sides. s and point the Upward Movem m out to ent Phase: All repetition Raise the dum Athlete Contraction Phase The energy for pulling action, Neuromuscular System Starting Positio s beg in from this pos ition. wide arc back bbells up tow ard each other or power stroke, comes from hydrolysis (breakdown) n: Spotter to the starting in a Keep the wri position. of adenosine triphosphate (ATP) to adenosine diphos- Muscle fibers are innervated by motor neurons that trans- Position one knee on the floo sts stiff and slightly flexed the elbows hel phate (ADP) and phosphate, a reaction catalyzed by the mit impulses in the form of electrochemical signals from the other leg forward and r with the foo t of position. d in a kneel on both flat on the floo Keep the han enzyme myosin adenosine triphosphatase (ATPase). the spinal cord to muscle. A motor neuron generally has knees). r (or ds, wrists, fore arms, and sho arms, elbows, Another molecule of ATP must replace the ADP on the numerous terminal branches at the end of its axon and Grasp the ath lete’s forearm ulders in the upper s near the wri Maintain the same vertical myosin crossbridge globular head in order for the head to thus innervates many different muscle fibers. The whole At the athlete sts. five-point bod plane. ’s signal, ass y contact pos detach from the active actin site and return to its original structure is what determines the muscle fiber type anddum its bbells to a ist with moving Upward Movem ition. position over the ent Phase: position. This allows the contraction process to continue characteristics, function, and involvement in exercise. Release the the athlete’s che Keep the han Spotter ath lete’s forearm st. ds near—but (if calcium is available to bind to troponin) or relaxation s sm oothly. athlete’s forearm not touching— Downward Mo the to occur (if calcium is not available). It may be noted Activation of Muscles vement Phase: Athlete bells ascend. s near the wri sts as the dum Lower the b- that calcium plays a role in regulating a large number When a motor neuron fires an impulse or action poten- dumbbells in level with the a wide arc unt shoulders or il they are MAJOR MUSCL of events in skeletal muscle besides contraction. These tial, all of the fibers that it serves are simultaneously chest. ES INVOLVED include glycolytic and oxidative energy metabolism, as activated and develop force. The extent of control of a pectoralis maj or, anterior del well as protein synthesis and degradation (10). toids muscle depends on the number of muscle fibers within each motor unit. Muscles that must function with great ▶ Calcium and ATP are necessary for cross- precision, such as eye muscles, may have motor units bridge cycling with actin and myosin fila- with as few as one muscle fiber per motor neuron. ments. Changes in the number of active motor units in these small muscles can produce the extremely fine gradations Recharge Phase Measurable muscle shortening in force that are necessary for precise movements of the transpires only when this sequence of events—binding eyeball. In contrast, the quadriceps muscle group, which of calcium to troponin, coupling of the myosin cross- moves the leg with much less precision, may have sev- bridge with actin, power stroke, dissociation of actin and eral hundred fibers served by one motor neuron. Steps of Muscle Contraction The steps of muscle contraction can be summarized as follows: 1. Initiation of ATP splitting (by myosin ATPase) causes myosin head to be in an “energized” state that allows it to move into a position to be able to form a bond with actin. Sidebars 2. The release of phosphate from the ATP splitting process then causes the myosin head to change shape and shift. Starting pos itions 3. This pulls the actin filament in toward the center of the sarcomere and is referred to as the power Downward and stroke; ADP is then released. upward mov eme nts 4. Once the power stroke has occurred, the myosin head detaches from the actin but 374 only after another ATP binds to the myosin head because the binding process facilitates detachment. 5. The myosin head is now ready to bind to another actin (as described in step 1), and the cycle contin- ues as long as ATP and ATPase are present and calcium is bound to the troponin. Exercise photos  Preface ix Student and Professional (NSCA) supports and disseminates research-based knowledge and its practical application to improve ath- Resources letic performance and fitness. With over 30,000 members The web resource with online video includes video of 21 in more than 50 countries, the NSCA has established resistance training exercises for use in understanding and itself as an international clearinghouse for strength and performing correct exercise technique. Lab activities are conditioning research, theories, and practices. provided to give students hands-on practice with testing The CSCS and NSCA-CPT were the first certifica- and evaluation. The fillable forms make completing and tions of their kind to be nationally accredited by the submitting lab assignments easy. National Commission for Certifying Agencies, a non- The web resource can be found at www.HumanKinetics governmental, nonprofit agency in Washington, DC, that.com/EssentialsOfStrengthTrainingAndConditioning. sets national standards for certifying agencies. To date, more than 40,000 professionals residing in 75 countries hold one or more NSCA certifications. Certification Exams Whether used for learning the essentials of strength Essentials of Strength Training and Conditioning is training and conditioning, for preparing for a certifica- the primary resource for individuals preparing for tion exam, or as a reference by professionals, Essentials the National Strength and Conditioning Association’s of Strength Training and Conditioning, Fourth Edition, Certified Strength and Conditioning Specialist (CSCS) will help practitioners and the scientific community certification exam. better understand how to develop and administer safe As a worldwide authority on strength and condition- and effective strength training and conditioning ing, the National Strength and Conditioning Association programs. 86 Essentials of Strength Training and Conditioning body and helping with the adaptive response to heavy plays an important role. The goal of this chapter has been resistance training. Whether trying to optimize a work- to provide an initial glimpse into this complex but also out or avoid overtraining, the strength and conditioning highly organized system that helps to mediate changes professional must remember that the endocrine system in the body with resistance exercise training. KEY TERMS allosteric binding site General Adaptation Syndrome polypeptide hormone Key terms anabolic hormone hormone proteolytic enzyme catabolic hormone hormone–receptor complex (H-RC) secondary messenger cross-reactivity lock-and-key theory steroid hormone diurnal variation neuroendocrine immunology target tissue cell downregulation neuroendocrinology thyroid hormone endocrine gland STUDY QUESTIONS 1. After a bout of resistance training, acute hormonal secretions provide all of the following information to the Study questions body EXCEPT a. amount of physiological stress b. metabolic demands of exercise c. type of physiological stress d. energy expended 2. Which of the following hormones enhance(s) muscle tissue growth? I. growth hormone II. cortisol III. IGF-I IV. progesterone a. I and III only b. II and IV only c. I, II, and III only d. II, III, and IV only 3. Which of the following is NOT a function of growth hormone? a. increase lipolysis b. decrease collagen synthesis c. increase amino acid transport d. decrease glucose utilization 4. Which of the following hormones has the greatest influence on neural changes? a. growth hormone b. testosterone c. cortisol d. IGF 5. What type of resistance training workout promotes the highest growth hormone increases following the exercise session? Rest Volume Sets a. 30 seconds High 3 b. 30 seconds Low 1 c. 3 minutes High 1 d. 3 minutes Low 3 This page intentionally left blank. ACCESSING THE LAB ACTIVITIES The lab activities are accessed through the web resource. Lab 7: Muscular Strength and Power Testing Individuals who purchase a new print book will Vertical Jump Test receive access to the web resource via a key code. Standing Long Jump Test The web resource can be accessed at www. HumanKinetics.com/EssentialsOfStrengthTrainingAnd 1RM Bench Press Conditioning. Following is a list of the lab activities. 1RM Back Squat Lab 1: Anaerobic Capacity Testing Lab 8: Techniques of Exercise 300-Yard (274 m) Shuttle Run Plyometric Exercise Techniques Lab 2: Aerobic Capacity Testing Lab 9: Speed and Agility Technique and Testing 1.5-Mile (2.4 km) Run T-Test 12-Minute Run Hexagon Test Pro Agility Test Lab 3: Anthropometry and Body Composition 40-Yard (37 m) Sprint Skinfold Measurements Lab 10: Muscular Endurance Testing Lab 4: Exercise Testing for Athletes Push-Up Test Test Selection and Order YMCA Bench Press Test Lab 5: Techniques of Exercise Partial Curl-Up Test Flexibility Exercise Techniques Lab 11: Facility Layout Design Lab 6: Techniques of Exercise Facility Floor Plan Resistance Exercise and Spotting Guidelines xi This page intentionally left blank. ACKNOWLEDGMENTS The development of the fourth edition of the NSCA’s I have to thank my family. My wife Erin has sacrificed Essentials of Strength Training and Conditioning was a everything to allow me the ability to chase my dreams massive undertaking that would not have been possible and undertake projects like this. Without her support I without the contributions of a vast number of people. The would merely be stuck under the heavy lifting bar of historic development of this iconic text has served as our life. It is a blessing to have someone strong enough to guiding principle, and the hard work of the numerous spot you when times are tough, and for that I love you authors who contributed to the three previous editions more than you know. For my father, Guy Haff—I doubt has established a strong foundation for this text. There- you ever thought that lifting weights would become fore, we thank the previous editors, Thomas Baechle my whole life’s work when you took me to the West and Roger Earle, for their foresight over twenty years Morris YMCA at 11 years of age to teach me to lift. With- ago that has led us to where we are today and for their out that I cannot imagine who I would be at this moment. passionate work on all of the previous editions. This edi- Finally, I must dedicate my efforts to my mother, Sandra tion would not have been possible without the continued Haff. No matter where you are now, I hope you are contribution of Roger Earle, who has gone beyond his still proud of the man I am and the man I strive to be role as a Human Kinetics representative. He is a true each and every day. I miss you much, Mom, and I wish friend who has helped with many aspects of this book you were here to see all the great things that have and our writing careers. happened. We would also like to thank Keith Cinea and Carwyn Sharp for their help throughout the process. These indi- N. Travis Triplett, PhD, CSCS,*D, FNSCA viduals have represented the NSCA well and positioned I never dreamed that taking my first weight training the science that underpins our profession as the standard class while at the university would have culminated that determines the content of this text. Because it is a in such a rewarding career in the field of strength and key resource for current and future strength and condi- conditioning. It is difficult to thank every person who tioning professionals, it was essential for us to ensure had a role in getting me to this point in my life and my that this text holds true to the NSCA mission of trans- career, which enabled me to enthusiastically embark lating science into practice, and both Keith and Carwyn on this project. I was fortunate to receive a strong are ambassadors of this philosophy. Thanks also to the foundation from my parents—I wish you could both multitude of individuals at Human Kinetics who were be here to see that the example you set was followed. essential to completing every phase of the publication I also want to thank my brother and my circle of of this book, from copyediting to graphic design. Prob- friends, who have always been supportive and have ably the most important note of thanks goes to Chris been there to brighten my day. Professionally, my two Drews and Karla Walsh, our developmental editor and greatest influences have been Mike Stone and Bill managing editor, who helped two novice book editors Kraemer. I value your mentorship and friendship in countless ways. Without Chris and Karla, we would greatly. Numerous colleagues and former students have probably been lost in the process. around the world have contributed to my knowledge and success along the way, and I appreciate each and G. Gregory Haff, PhD, CSCS,*D, FNSCA every one of you even if we don’t see each other very To my coeditor and long-time friend, Travis Triplett: I often. could think of no one else I would want to edit a book Finally, to my co-editor and good friend, Greg Haff: of this magnitude with. Your kind heart and easygoing Who would have thought that sitting around at the lunch style is a perfect complement to my “bull in a china buffet as graduate students talking strength and condi- shop” methodology for processes like this. Thanks for tioning would have led to this? I look forward to many always being one of my very best friends! more years of friendship and collaboration. xiii This page intentionally left blank. CREDITS Figure 2.5 Reprinted, by permission, from B.A. Gowitzke cemic index and glycemic load values,” American Journal of and M. Milner, 1988. Scientific bases of human movement, Clinical Nutrition 76: 5-56. © American Society for Nutrition. 3rd ed. (Baltimore, MD: Lippincott, Williams & Wilkins), Table 9.10 Reprinted, by permission, from M.N. Sawka 184-185. et al., 2007, “American College of Sports Medicine position Figure 2.10 Reprinted, by permission, from E.A. Harman, stand. Exercise and fluid replacement,” Medicine and Science M. Johnson, and P.N. Frykman, 1992, “A movement-oriented of Sport and Exercise 39: 377-390, 2007. approach to exercise prescription,” NSCA Journal 14 (1): Table 10.5 Reprinted, by permission, from National Heart, 47-54. Lung, and Blood Institute, 1998, “Clinical guidelines on the Figure 2.13 Reprinted from K. Jorgensen, 1976, “Force- identification, evaluation, and treatment of overweight and velocity relationship in human elbow flexors and extensors.” obesity in adults: The evidence report,” Obesity Research In Biomechanics A-V, edited by P.V. Komi (Baltimore, MD: 6: 464. University Park Press), 147. By permission of P.V. Komi. Table 10.6 Reprinted, by permission, from National Heart, Figure 4.5 Reprinted from Steroids, Vol. 74(13-14), J.L. Lung, and Blood Institute, 1998, “Clinical guidelines on the Vingren, W.J. Kraemer, et al., “Effect of resistance exercise identification, evaluation, and treatment of overweight and on muscle steroid receptor protein content in strength trained obesity in adults: The evidence report,” Obesity Research men and women,” pgs. 1033-1039, copyright 2009, with 6: 464. permission from Elsevier. Figure 13.6 Adapted, by permission, from G.M. Gilliam, Figure 4.7 Adapted from W.J. Kraemer et al., 1998, “Hor- 1983, “300 yard shuttle run,” NSCA Journal 5 (5): 46. monal responses to consecutive days of heavy-resistance exer- Figure 13.11 Adapted, by permission, from D. Semenick, cise with or without nutritional supplementation,” Journal of 1990, “Tests and measurements: The T-test,” NSCA Journal Applied Physiology 85 (4): 1544-1555. Used with permission. 12(1): 36-37. Table 5.3 Reprinted, by permission, from A. Fry, 1993, Figure 13.12 Adapted, by permission, from K. Pauole et “Physiological responses to short-term high intensity resis- al., 2000, “Reliability and validity of the T-test as a measure tance exercise overtraining,” Ph.D. Diss., The Pennsylvania of agility, leg power, and leg speed in college age males and State University; Meeusen R, Duclos M, Foster C, Fry A, females,” Journal of Strength and Conditioning Research Gleeson et al., 2013, “Prevention, diagnosis, and treatment 14: 443-450. of the over training syndrome: joint consensus statement of Figure 13.16 Reprinted, by permission, from M.P. Reiman, the European College of Sports Science and the American 2009, Functional testing in performance (Champaign, IL: College of Sports Medicine,” Medicine and Science in Sport Human Kinetics), 109. and Exercise 45: 186-205. Table 13.1 Adapted, by permission, from J. Hoffman, 2006, Figure 7.2 Reprinted, by permission, from A.D. Faigen- Norms for fitness, performance, and health (Champaign, IL: baum et al., 2013, “Youth resistance training: past practices, Human Kinetics), 36-37. new perspectives and future directions,” Pediatric Exercise Table 13.2 Reprinted, by permission, from J. Hoffman, 2006, Science 25: 591-604. Norms for fitness, performance, and health (Champaign, IL: Figure 7.3a © Hossler, PhD/Custom Medical Stock Photo— Human Kinetics), 36-37. All rights reserved. Table 13.3 Reprinted, by permission, from J. Hoffman, 2006, Figure 7.3b © SPL/Custom Medical Stock Photo—All Norms for fitness, performance, and health (Champaign, IL: rights reserved. Human Kinetics), 38. Figure 8.1 Reprinted, by permission, from R.S. Weinberg Table 13.5 Reprinted, by permission, from J. Hoffman, 2006, and D. Gould, 2015, Foundations of sport and exercise psy- Norms for fitness, performance, and health (Champaign, IL: chology, 6th ed. (Champaign, IL: Human Kinetics), 79. Human Kinetics), 58. Adapted from D.A. Chu, 1996, Explosive Figure 8.2 Reprinted, by permission, from B.D. Hatfield and power and strength (Champaign, IL: Human Kinetics). G.A. Walford, 1987, “Understanding anxiety: Implications for Table 13.6 Reprinted, by permission, from J. Hoffman, 2006, sport performance,” NSCA Journal 9(2): 60-61. Norms for fitness, performance, and health (Champaign, IL: Table 9.6 Adapted, by permission, from K. Foster-Powell, S. Human Kinetics), 58; adapted from D.A. Chu, 1996, Explosive Holt, and J.C. Brand-Miller, 2002, “International table of gly- power and strength (Champaign, IL: Human Kinetics). xv xvi Credits Table 13.10 Reprinted, by permission, from American Col- Table 19.4 Adapted, by permission, from S. Nimphius, lege of Sports Medicine, 2014, ACSM's guidelines for exercise 2014, Increasing agility. In High-performance training for testing and prescription, 9th ed. (Baltimore, MD: Lippincott, sports, edited by D. Joyce and D. Lewindon (Champaign, IL: Williams, and Wilkins), 101. Human Kinetics), 194. Table 13.11 Source: Canadian Physical Activity, Fitness Table 19.5 Adapted, by permission, from S. Nimphius, 2014, & Lifestyle Approach: CSEP-Health & Fitness Program's Increasing agility. In High-performance training for sports, Appraisal & Counselling Strategy, Third Edition, © 2003. edited by D. Joyce and D. Lewindon (Champaign, IL: Human Reprinted with permission from the Canadian Society for Kinetics), 185-198. Exercise Physiology. Table 20.2 Reprinted, by permission, from NSCA, 2012, Table 13.19 Adapted, by permission, from ACSM, 2014, Aerobic endurance training program design, by P. Hagerman. ACSM’s guidelines for exercise testing and prescription, 9th In NSCA’s essentials of personal training, 2nd ed., edited ed. (Philadelphia: Wolters Kluwer Health/Lippincott Williams by J.W. Coburn and M.H. Malek (Champaign, IL: Human & Wilkins), 88. Kinetics), 395. Table 13.22 Reprinted, by permission, from J. Hoffman, Figure 21.1 Adapted, by permission, from G.G. Haff and 2006, Norms for fitness, performance, and health (Champaign, E.E. Haff, 2012, Training integration and periodization. IL: Human Kinetics), 113. In NSCA’s guide to program design, edited by J. Hoffman Table 13.25 Adapted, by permission, from V. H. Heyward, (Champaign, IL: Human Kinetics), 215. 1998, Advanced fitness assessment and exercise prescription, Figure 21.2 Adapted, by permission, from G.G. Haff and 3rd ed. (Champaign, IL: Human Kinetics), 155. E.E. Haff, 2012, Training integration and periodization. Table 13.26 Adapted, by permission, from V. H. Heyward, In NSCA’s guide to program design, edited by J. Hoffman 1998, Advanced fitness assessment and exercise prescription, (Champaign, IL: Human Kinetics), 216. 3rd ed. (Champaign, IL: Human Kinetics), 12. Figure 21.3 Adapted, by permission, from G.G. Haff and Table 16.1 Adapted, by permission, from D.T. McMaster, J. E.E. Haff, 2012, Training integration and periodization. Cronin, and M. McGuigan, 2009, “Forms of variable resistance In NSCA’s guide to program design, edited by J. Hoffman training,” Strength & Conditioning Journal 31: 50-64. (Champaign, IL: Human Kinetics), 219. Table 16.2 Adapted, by permission, from D.T. McMaster, Table 21.1 Adapted from G.G. Haff and E.E. Haff, 2012, J. Cronin, and M. McGuigan, 2010, “Quantification of rubber Training integration and periodization. In NSCA’s guide to and chain-based resistance modes,” Journal of Strength and program design, edited by J. Hoffman (Champaign, IL: Human Conditioning Research 24: 2056-2064. Kinetics), 220. Figure 17.1 Reprinted, by permission, from R.W. Earle, Figure 21.4 Reprinted, by permission, from G.G. Haff 2006, Weight training exercise prescription. In: Essentials of and E.E. Haff, 2012, Training integration and periodization. personal training symposium workbook (Lincoln, NE: NSCA In NSCA’s guide to program design, edited by J. Hoffman Certification Commission), 2006 (Champaign, IL: Human Kinetics), 223; adapted from figure Figure 17.2 Reprinted, by permission, from R.W. Earle, 11.7, p. 2239. Reprinted from Weight Training: A Scientific 2006, Weight training exercise prescription. In: Essentials of Approach, 2nd edition, by Michael H. Stone and Harold St. personal training symposium workbook (Lincoln, NE: NSCA O’Bryant, copyright © 1987 by Burgess. Certification Commission). Table 23.1 Adapted, by permission, from W. Kroll, 1991, Figure 19.1 Reprinted, by permission, from K. Häkki- “Structural and functional considerations in designing the nen, K. and P.V. Komi, 1985, “The effect of explosive type facility, part I,” NSCA Journal 13(1): 51-58, 1991 strength training on electromyographic and force production Figure 23.6 Adapted, by permission, from National Strength characteristic of leg extensor muscles during concentric and and Conditioning Association, 2004, NSCA’s essentials of various stretch-shortening cycle exercises,” Scandinavian personal training, edited by R.W. Earle and T.R. Baechle Journal of Sports Sciences 7(2): 65-76. Copyright 1985 (Champaign, IL: Human Kinetics), 604-606. Munksgaard International Publishers, Ltd. Copenhagen, Table 24.1 Adapted, by permission, from NSCA, 2009, Denmark. Strength & conditioning professional standards and guidelines Figure 19.3 Reprinted, by permission, from K.P. Clark and (Colorado Springs, CO: NSCA), 17. P.G. Weyand, 2014, “Are running speeds maximized with Figure 24.3 Reprinted, by permission, from R.W. Earle, simple-spring stance mechanics?” Journal of Applied Physi- 1993, Staff and facility policies and procedures manual ology 117(6): 604-615 (Omaha, NE: Creighton University). Figure 19.11 Reprinted, by permission, from S.S. Plisk and Table 24.2 Adapted, by permission, from NSCA, 2011, Per- V. Gambetta, 1997, “Tactical metabolic training,” Strength & formance training center emergency policies and procedures Conditioning 19(2): 44-53. manual (Colorado Springs, CO: NSCA), 3. CHAPTER Structure and Function 1 of Body Systems N. Travis Triplett, PhD After completing this chapter, you will be able to describe both the macrostructure and microstructure of muscle and bone, describe the sliding-filament theory of muscular contraction, describe the specific morphological and physiological characteristics of different muscle fiber types and predict their relative involvement in different sport events, and describe the anatomical and physiological characteristics of the cardiovascular and respiratory systems. The author would like to acknowledge the significant contributions of Robert T. Harris and Gary R. Hunter to this chapter. 1 2 Essentials of Strength Training and Conditioning Physical exercise and sport performance involve There are approximately 206 bones in the body, effective, purposeful movements of the body. These though the number can vary. This relatively light, strong movements result from the forces developed in muscles, structure provides leverage, support, and protection which move the various body parts by acting through (figure 1.1). The axial skeleton consists of the skull lever systems of the skeleton. These skeletal muscles are (cranium), vertebral column (vertebra C1 through the under the control of the cerebral cortex, which activates coccyx), ribs, and sternum. The appendicular skele- the skeletal muscle cells or fibers through the motor ton includes the shoulder (or pectoral) girdle (left and neurons of the peripheral nervous system. Support for right scapula and clavicle); bones of the arms, wrists, this neuromuscular activity involves continuous delivery and hands (left and right humerus, radius, ulna, carpals, of oxygen and nutrients to working tissues and removal metacarpals, and phalanges); the pelvic girdle (left and of carbon dioxide and metabolic waste by-products from right coxal or innominate bones); and the bones of the working tissues through activities of the cardiovascular legs, ankles, and feet (left and right femur, patella, tibia, and respiratory systems. fibula, tarsals, metatarsals, and phalanges). In order to best apply the available scientific knowl- Junctions of bones are called joints. Fibrous joints edge to the training of athletes and the development of (e.g., sutures of the skull) allow virtually no movement; effective training programs, strength and conditioning cartilaginous joints (e.g., intervertebral disks) allow professionals must have a basic understanding of not limited movement; and synovial joints (e.g., elbow only musculoskeletal function but also those systems and knee) allow considerable movement. Sport and of the body that directly support the work of exercising exercise movements occur mainly about the synovial muscle. Accordingly, this chapter summarizes those joints, whose most important features are low friction aspects of the anatomy and function of the musculo- and large range of motion. Articulating bone ends are skeletal, neuromuscular, cardiovascular, and respiratory covered with smooth hyaline cartilage, and the entire systems that are essential for developing and maintaining joint is enclosed in a capsule filled with synovial fluid. muscular force and power. There are usually additional supporting structures of ligament and cartilage (13). Musculoskeletal System Virtually all joint movement consists of rotation about points or axes. Joints can be categorized by the number The musculoskeletal system of the human body consists of directions about which rotation can occur. Uniaxial of bones, joints, muscles, and tendons configured to joints, such as the elbow, operate as hinges, essentially allow the great variety of movements characteristic of rotating about only one axis. The knee is often referred to human activity. This section describes the various com- as a hinge joint, but its axis of rotation actually changes ponents of the musculoskeletal system, both individually throughout the joint range of motion. Biaxial joints, and in the context of how they function together. such as the ankle and wrist, allow movement about two perpendicular axes. Multiaxial joints, including the Skeleton shoulder and hip ball-and-socket joints, allow movement The muscles of the body do not act directly to exert force about all three perpendicular axes that define space. on the ground or other objects. Instead, they function The vertebral column is made up of vertebral bones by pulling against bones that rotate about joints and separated by flexible disks that allow movement to occur. transmit force to the environment. Muscles can only The vertebrae are grouped into 7 cervical vertebrae in pull, not push; but through the system of bony levers, the neck region; 12 thoracic vertebrae in the middle to muscle pulling forces can be manifested as either pulling upper back; 5 lumbar vertebrae, which make up the lower or pushing forces against external objects. back; 5 sacral vertebrae, which are fused together and What Factors Affect Skeletal Growth in an Adult? There are several things that can positively affect the adult skeleton, and most are a result of muscle use. When the body is subjected to heavy loads (job tasks or resistance training), the bone will increase in density and bone mineral content. If the body performs more explosive movements with impact, similar changes can occur. Some of the higher bone densities have been seen in people who engage in gymnastics or other activities that involve high-strength and high-power movements, some with hard landings (11). Other factors that influence bone adaptations are whether the axial skeleton is loaded and how often this loading occurs (frequency). Since the adaptation period of bone is longer than that of skeletal muscle, it is important to vary the stimulus in terms of frequency, intensity, and type.  Structure and Function of Body Systems 3 Clavicle Scapula Sternum Humerus Ribs Vertebral column Crest of pelvis (iliac crest) Pelvis Radius Ulna Carpals Metacarpals Femur Patella Tibia Fibula Metatarsals a b Figure 1.1 (a) Front view and (b) rear view of an adult male human skeleton. E6372/NSCA/fig01.01/508626/alw/r1-pulled make up the rear part of the pelvis; and 3 to 5 coccygeal Fibrous connective tissue, or epimysium, covers the vertebrae, which form a kind of vestigial internal tail body’s more than 430 skeletal muscles. The epimysium extending downward from the pelvis. is contiguous with the tendons at the ends of the muscle (figure 1.3). The tendon is attached to bone periosteum, Skeletal Musculature a specialized connective tissue covering all bones; any contraction of the muscle pulls on the tendon and, in The system of muscles that enables the skeleton to move turn, the bone. Limb muscles have two attachments to is depicted in figure 1.2. The connection point between bone: proximal (closer to the trunk) and distal (farther bones is the joint, and skeletal muscles are attached to from the trunk). The two attachments of trunk muscles bones at each of their ends. Without this arrangement, are termed superior (closer to the head) and inferior movement could not occur. (closer to the feet). Muscle cells, often called muscle fibers, are long Musculoskeletal Macrostructure (sometimes running the entire length of a muscle), cylin- and Microstructure drical cells 50 to 100 µm in diameter (about the diameter Each skeletal muscle is an organ that contains muscle of a human hair). These fibers have many nuclei situated tissue, connective tissue, nerves, and blood vessels. on the periphery of the cell and have a striated appearance  Trapezius Deltoid Infraspinatus Pectoralis major Teres major Biceps brachii Triceps brachii Rectus abdominis Brachialis Latissimus dorsi External oblique Brachioradialis Finger extensors Finger flexors Adductor longus Gluteus maximus Gracilis Semitendinosus Sartorius Biceps femoris Rectus femoris Semimembranosus Vastus lateralis Vastus medialis Gastrocnemius Tibialis anterior Soleus a b Figure 1.2 (a) Front view and (b) rear view of adult male human skeletal musculature. E6372/NSCA/fig01.02a/508073/alw/r1-pulled E6372/NSCA/fig01.02b/508074/alw/r1-pulled Tendon Muscle belly Epimysium (deep fascia) Fasciculus Endomysium (between fibers) Sarcolemma Sarcoplasm Myofibril Perimysium Myofilaments actin (thin) myosin (thick) Single muscle fiber Nucleus Figure 1.3 Schematic drawing of a muscle illustrating three types of connective tissue: epimysium (the outer layer), perimysium (surrounding each fasciculus, or group of fibers), and endomysium (surrounding individual fibers). 4 E6372/NSCA/fig01.03/508017/alw/r1-pulled  Structure and Function of Body Systems 5 under low magnification. Under the epimysium the Mitochondrion Opening to T-tubule muscle fibers are grouped in bundles (fasciculi) that may consist of up to 150 fibers, with the bundles sur- rounded by connective tissue called perimysium. Each muscle fiber is surrounded by connective tissue called endomysium, which is encircled by and is contiguous with the fiber’s membrane, or sarcolemma (13). All the connective tissue—epimysium, perimysium, and endomysium—is contiguous with the tendon, so tension developed in a muscle cell is transmitted to the tendon and the bone to which it is attached (see figure 1.3). The junction between a motor neuron (nerve cell) Sarcoplasmic T-tubule reticulum and the muscle fibers it innervates is called the motor end plate, or, more often, the neuromuscular junction Myofibril Sarcolemma (figure 1.4). Each muscle cell has only one neuromuscu- lar junction, although a single motor neuron innervates Figure 1.5 Sectional view of a muscle fiber. many muscle fibers, sometimes hundreds or even thou- sands. A motor neuron and the muscle fibers it innervates are called a motor unit. All the muscle fibers of a motor of protein filaments, other proteins, stored glycogen and E6372/NSCA/fig01.05/508019/alw/r1-pulled unit contract together when they are stimulated by the fat particles, enzymes, and specialized organelles such motor neuron. as mitochondria and the sarcoplasmic reticulum. The interior structure of a muscle fiber is depicted in Hundreds of myofibrils (each about 1 mm in diam- figure 1.5. The sarcoplasm, which is the cytoplasm of a eter, 1/100 the diameter of a hair) dominate the sarco- muscle fiber, contains contractile components consisting plasm. Myofibrils contain the apparatus that contracts the muscle cell, which consists primarily of two types Dendrites of myofilament: myosin and actin. The myosin fila- ments (thick filaments about 16 nm in diameter, about Nucleus 1/10,000 the diameter of a hair) contain up to 200 myosin molecules. The myosin filament consists of a globular head, a hinge point, and a fibrous tail. The globular heads protrude away from the myosin filament at regular intervals, and a pair of myosin filaments forms a cross- bridge, which interacts with actin. The actin filaments Axon (thin filaments about 6 nm in diameter) consist of two strands arranged in a double helix. Myosin and actin filaments are organized longitudinally in the smallest contractile unit of skeletal muscle, the sarcomere. Sarco- Node of Ranvier meres average about 2.5 mm in length in a relaxed fiber (approximately 4,500 per centimeter of muscle length) Myelin sheath and are repeated the entire length of the muscle fiber (1). Figure 1.6 shows the structure and orientation of the myosin and actin in the sarcomere. Adjacent myosin filaments anchor to each other at the M-bridge in the Neuromuscular center of the sarcomere (the center of the H-zone). Actin junction filaments are aligned at both ends of the sarcomere and are anchored at the Z-line. Z-lines are repeated through Muscle the entire myofibril. Six actin filaments surround each myosin filament, and each actin filament is surrounded by three myosin filaments. It is the arrangement of the myosin and actin fil- aments and the Z-lines of the sarcomeres that gives Figure 1.4 A motor unit, consisting of a motor neuron skeletal muscle its alternating dark and light pattern, and the muscle fibers it innervates. There are typically which appears as striated under magnification. The dark several hundred muscle fibers in a single motor unit. A-band corresponds with the alignment of the myosin E6372/NSCA/fig01.04/508018/alw/r1-pulled 6 Essentials of Strength Training and Conditioning Actin filament Myosin filament Myofilaments (cross sections) Myofibril M-line I-band A-band I-band A-band Z-line H-zone Z-line M-line Resting state Sarcomere Myosin (thick) filament Head Tail Backbone Tropomyosin Actin (thin) filament Actin Troponin Actin Cross-bridge Myosin Z-line end M-bridge H-zone level Figure 1.6 Detailed view of the myosin and actin protein filaments in muscle. The arrangement of myosin (thick) and actin (thin) filaments gives skeletal muscle its striated appearance. filaments, whereas the light I-band corresponds with the sarcomere. The I-band also decreases as the Z-lines are E6372/NSCA/fig01.06/508020/alw/r1-pulled areas in two adjacent sarcomeres that contain only actin pulled toward the center of the sarcomere. filaments (13). The Z-line is in the middle of the I-band Parallel to and surrounding each myofibril is an and appears as a thin, dark line running longitudinally intricate system of tubules, called the sarcoplasmic through the I-band. The H-zon