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FITNESS: THE COMPLETE GUIDE OFFICIAL TEXT FOR ISSA’S CERTIFIED FITNESS TRAINER PROGRAM
issaonline.edu
Frederick C. Hatfield, PhD
Contributors Frederick C. Hatfield, PhD Sal Arria, DC, MSS Patrick S. Gamboa, MBA, MSS Josh Bryant, MS, MFS Paul O. Davis, PhD, FASCM Michael Yessis, PhD James A. Peterson, PhD Charles Staley, BS, MSS John Berardi, PhD Brian St. Pierre, MS, RD Ryan Andrews, MS, MA, RD Karl Knopf, EdD Thomas D. Fahey, EdD Darin Rell, BS, CFT, AHA, BLS Instructor
Reviewers Cameron Baker, BS, MFS Josh Bryant, MS, MFS
Editors Peter A. Balaskas Joanna Hatzopoulos
Graphics and Illustration Sarah McDonough, Art Director Karen Williams, Senior Artist, Illustrator Alex Gundersen, Illustrator Samantha Hird, Photography (Flexibility)
Fitness: The Complete Guide (Edition 9.0) Official course text for: International Sports Sciences Association’s Certified Fitness Trainer Course 10 9 8 7 6 5 4 3 2 1
Copyright © 2015 TXu1-157-866 International International Sports Sciences Association. Published by the International Sports Sciences Association, Carpinteria, CA 93013. All rights reserved. No part of this work may be reproduced reproduced or transmitted in any form or by any electronic, electronic, mechanical, or other means, means, now known or hereafter invented, including xerography, photocopying, and recording, or in any information storage and retrieval system without the written permission of the publisher. Direct copyright, permissions, reproduction, and publishing inquiries to: International Sports Sciences Association, 1015 Mark Avenue, Carpinteria, CA 93013 1.800.892.4772 • 1.805.745.8111 (local) • 1.805.745.8119 (fax)
DISCLAIMER OF WARRANTY This text is informational only. The data and information contained herein are based upon information from various published and unpublished sources that represents training, health, and nutrition literature and practice summarized by the author and publisher. The publisher of this text makes no warranties, expressed or implied, regarding the currency, completeness, or scientific accuracy of this information, nor does it warrant the fitness of the information for any particular purpose. The information is not intended for use in connection with the sale of any product. Any claims or presentations regarding any specific products or brand names are strictly the responsibility of the product owners or manufacturers. This summary of information from unpublished sources, books, research journals, and articles is not intended to replace the advice or attention of health care professionals. It is not intended to direct their behavior or replace their independent professional judgment. If you have a problem or concern with your health, or before you embark on any health, fitness, or sports training programs, seek clearance and guidance from a qualified health care professional.
Contributors Frederick C. Hatfield, PhD Sal Arria, DC, MSS Patrick S. Gamboa, MBA, MSS Josh Bryant, MS, MFS Paul O. Davis, PhD, FASCM Michael Yessis, PhD James A. Peterson, PhD Charles Staley, BS, MSS John Berardi, PhD Brian St. Pierre, MS, RD Ryan Andrews, MS, MA, RD Karl Knopf, EdD Thomas D. Fahey, EdD Darin Rell, BS, CFT, AHA, BLS Instructor
Reviewers Cameron Baker, BS, MFS Josh Bryant, MS, MFS
Editors Peter A. Balaskas Joanna Hatzopoulos
Graphics and Illustration Sarah McDonough, Art Director Karen Williams, Senior Artist, Illustrator Alex Gundersen, Illustrator Samantha Hird, Photography (Flexibility)
Fitness: The Complete Guide (Edition 9.0) Official course text for: International Sports Sciences Association’s Certified Fitness Trainer Course 10 9 8 7 6 5 4 3 2 1
Copyright © 2015 TXu1-157-866 International International Sports Sciences Association. Published by the International Sports Sciences Association, Carpinteria, CA 93013. All rights reserved. No part of this work may be reproduced reproduced or transmitted in any form or by any electronic, electronic, mechanical, or other means, means, now known or hereafter invented, including xerography, photocopying, and recording, or in any information storage and retrieval system without the written permission of the publisher. Direct copyright, permissions, reproduction, and publishing inquiries to: International Sports Sciences Association, 1015 Mark Avenue, Carpinteria, CA 93013 1.800.892.4772 • 1.805.745.8111 (local) • 1.805.745.8119 (fax)
DISCLAIMER OF WARRANTY This text is informational only. The data and information contained herein are based upon information from various published and unpublished sources that represents training, health, and nutrition literature and practice summarized by the author and publisher. The publisher of this text makes no warranties, expressed or implied, regarding the currency, completeness, or scientific accuracy of this information, nor does it warrant the fitness of the information for any particular purpose. The information is not intended for use in connection with the sale of any product. Any claims or presentations regarding any specific products or brand names are strictly the responsibility of the product owners or manufacturers. This summary of information from unpublished sources, books, research journals, and articles is not intended to replace the advice or attention of health care professionals. It is not intended to direct their behavior or replace their independent professional judgment. If you have a problem or concern with your health, or before you embark on any health, fitness, or sports training programs, seek clearance and guidance from a qualified health care professional.
About the Author | iii
ABOUT THE AUTHOR Frederick C. Hatfield, MSS, PhD, is co-ounder and president o the ISSA. Dr. Hatfield, (aka “Dr. Squat”) won the World Championship three times in the sport o powerlifing and perormed a competitive squat with 1014 pounds at a body weight o 255 pounds (more weight than anyone in history had ever lifed in competition). Dr. Hatfield’s ormer positions include an assistant proessorship at the University o Wisconsin (Madison) and senior vice president and director o research and development or Weider Health and Fitness, Incorporated. Dr. Hatfield was honored by Southern Connecticut State University when they presented him with the 1991 Alumni Citation Award. He has written over 60 books (including several best-sellers) best-sellers) and hundreds o articles in t he general areas o sports train ing, fitness, bodybuilding, and perormance nutrition. He has been coach a nd training consultant or several worl world-ranked d-ranked and pro proessional essional athletes, sports governing bodies, and proessional teams worldwide. Dr. Hatfield qualified or the 1998 World Championships Champio nships in Olympic Lifing and competed in t he Masters Division.
International Sports Sciences Association
TABLE OF CONTENTS Introduction, p. 1 SECTION ONE ANATOMY AND PHYSIOLOGY, p. 9 1 Metabolism, p. 11 2 Basic Anatomy and Physiology, p. 29 3 Musculoskeletal Anatomy and Physiology, p. 71 SECTION TWO KINESIOLOGY AND BIOMECHANICS, p. 113 4 Kinesiology of Exercise, p. 115 5 Biomechanics of Exercise, p. 131 6 Musculoskeletal Deviations, p. 149 7 Muscle Mechanics, p. 161
SECTION THREE HEALTH AND PHYSICAL FITNESS, p. 181 8 Strength, p. 183 9 Cardiovascular Training, p. 301 10 Flexibility Training, p. 333 11 Body Composition, p. 359
SECTION SIX FITNESS FOR ALL Topics in Fitness for Special Populations , p. 615 21 Exercise and Older Adults, p. 617 22 Exercise and Adaptive Fitness, p. 627 23 Exercise and Our Youth, p. 635 24 Exercise and Hypertension, p. 641
SECTION FOUR PROGRAM DEVELOPMENT, p. 381 12 Drawing-In Phase, p. 383 13 Basic Assessment of Fitness Participants, p. 393 14 Training Principles, p. 415 15 Periodization, p. 459 16 Determining Training Loads, p. 477 SECTION FIVE NUTRITION, p. 495 17 The Big Picture of Nutrition, p. 497 18 Nutritional Physiology, p. 517 19 Nutritional Science, p. 545 20 Nutritional Coaching, p. 575
25 Exercise and Diabetes, p. 647 26 Exercise and Arthritis, p. 653 27 Exercise and Coronary Heart Disease, p. 659 28 Exercise and Pregnancy, p. 665 29 Exercise and Asthma, p. 671 30 Sports Medicine in the Trenches, p. 677 31 Basic First Aid, p. 715 References, p. 725 Glossary, p. 737 Index, p. 759
TOPICS COVERED IN THIS UNIT Personal Training Who Wants Personal Training? What is a Personal Trainer? Why is Personal Training Necessary? What Should a Personal Trainer Know? ISSA Code of Ethics and Standards Principles and Purpose Academic Standards Professional Standards
INTRODUCTION
THE WHO, WHAT, WHY, AND HOW OF PERSONAL TRAINING
2 | Introduction
U.S. President Theodore Roosevelt
PERSONAL TRAINING oday’s fitness industry is a multibillion-dollar business. Personal training is its ever-growing offspring. Te roots o personal training are difficult to pinpoint. Some credit its origin to be in the 1950s (when personal trainers were first actively certified), although one could contend that personal training dates back to the beginning o recorded history. While the proession and terminology associated with personal training were not yet in existence, the concept o optimal health (which is the motivation behind the proession) was already being touted by ancient philosophers. Around 400 BC, Hippocrates wrote this: “Eating alone will not keep a man well; he must also take exercise. For food and exercise, while possessing opposite qualities, yet work together to produce health … and it is necessary, as it appears, to discern the power of various exercises, both natural exercises and artificial, to know which of them tends to increase flesh and which to lessen it; and not only this, but also to proportion exercise to bulk of food, to the constitution of the patient, to the age of the individual.”
Fitness: The Complete Guide
O all o the leaders o the United States, Teodore Roosevelt was one o the strongest presidents, both physically and mentally. However, he did not start that way. As a child, Roosevelt was small or his age and quite sickly. He had debilitating asthma, had poor eyesight, and was extremely thin. When he was 12 years old, his ather told him, “You have the mind, but you have not the body, and without the help of the body, the mind cannot go as far as it should. You must make the body.” (Morris, 1979). Roosevelt began spending every day building his body as well as his mind. He worked out with weights, hiked, hunted, rowed, and boxed. History can attest: Teodore Roosevelt’s strength in mind and body contributed to his strength as the leader o his nation. Another great leader was U.S. President John Kennedy. Like Roosevelt, Kennedy acknowledged the benefits o physical activity or optimal health. He once said, “Physical fitness is not only one of the most important keys to a healthy body, it is the basis of dynamic and creative intellectual activity.”
The Who, What, Why, and How of Personal Training | 3
WHO WANTS PERSONAL TRAINING?
WHAT IS A PERSONAL TRAINER?
According to the International Health, Racquet & Sports Club Association and American Sports Data (IHRSA/ ASD) Health Club rend Report, since 1998, the number o Americans belonging to health clubs has grown 45 percent (about 14 million members). Health club memberships among children under 18 years o age have jumped by 187 percent since 1987. Te number o clients considering personal training services continues to grow. According to IHR SA’s Annual Health Club C onsumer Study (2014), 52.9 mill ion Americans aged 6 years and older are members o health clubs. Over 12 percent o these members pay or the services o a personal trainer and over 6 million health club members alone paid or a personal trainer this past year. In-home sessions, park boot camp sessions, and other non traditional training sessions were not included in gym data.
Te proession o personal training is a relatively new field that continues to expand its boundaries and redefine itsel. Prior to the early 1980s, no minimal requirements existed to qualiy or identiy a person as a personal trainer. Tose engaged in training were still an esoteric group. Many learned about training solely through personal experiences in the gym. Recognizing the need or standardization and credibility, Dr. Sal Arria and Dr. Fred Hatfield pioneered a program o personal fitness training that merged gym experience with practical and applied sciences.
Here are some statistics from the report: •
Three out of five clients are women.
•
Clients report an average of 18 sessions with a trainer.
•
Trainers charge between $15 and $100 per hour—an average of $50 per hour.
•
Average sessions used in 12 months are as follows: Sessions Percentage 1–6 47% 7–11 12% 12–24 11% 25–49 8% 50 + 11% Not Reported
•
11%
Number of sessions clients used by age are as follows: Age Range Sessions 6–11 22 12–17 26 18–34 15 35–54 14 55 +
24
Tese statistics support the growing trend and need or personal training services. While those 4 million people who purchased personal training services are sold on the need or personal training, let’s explore what exactly is a personal trainer?
oday, a personal fitness trainer can be defined as a person who educates and trains clients in the perormance o sae and appropriate exercises in order to effect ively lead them to optimal health. Personal trainers can be sel-employed or work in health clubs, physicians’ offices, physical therapy clinics, wellness centers, hospitals, rehabilitation acilities, and private studios.
WHY IS PERSONAL TRAINING NECESSARY? Te U.S. Surgeon General’s Report on Physical Activity and Health supports the role o physical activity or good health and disease prevention. Te National Institutes o Health released a consensus statement on the importance o physical activity or cardiovascular health (US Department o Health and Human Services,). In addition, the Centers or Disea se Control and Prevention (CDC) launched the Healthy People Initiative, which lists physical activity, fitness, and nutrition at the top o twenty-two priority areas. Finally, the American Heart Association included physical inactivity and low fitness levels as primary risk actors, along with smoking, hypertension, and high cholesterol. Unortunately, although t he resounding benefits o physical activity and fitness are touted and reported, the United States is currently undergoing an obesity epidemic. In the United States, 25 to 35 percent o people remain sedentary. o make matters worse, ederal resources and unds or physical activity have lagged ar behind other aspects o health. Health and physical education in schools are low priorities, and when districts are looking to trim their budgets, health and physical education programs are ofen the first to be cut.
International Sports Sciences Association
4 | Introduction
Consider the ollowing: Each year in the United States, people spend $2.5 trillion on health care. Tis meteoric figure translates into an expenditure o almost $7,000 or each member o the U.S. population. Regret tably, this financial commitment has neither shown signs o abating nor has it produced satisactory results with regard to treating a wide variety o chronic health problems. Attempts to identiy the actors that have been major contributions to this virtual epidemic o medical problems have produced a litany o probable reasons why such a large number o individuals are so apparently unhealthy, including poor eating habits, sedentary liestyle, stress, and poor health habits (e.g., smoking). At the same time, a number o studies have been undertaken to identiy what, i anything, can be done to diminish either the number or the severity o medical problems affecting the public. Tese studies have provided considerable evidence that exercise has substantial medicinal benefits or people o all ages. wo o the most widely publicized efforts to investigate the possible relationship between exercise and disease were longitudinal studies, each o which involved more than 10,000 subjects. In a renowned study o 17,000 Harvard graduates, Ralph Paffenbarger, MD, ound that men who expended approximately 300 calories a day (the equivalent o walking briskly or 45 minutes) reduced their death rates rom all causes by an extraordinary 28 percent and lived an average o more tha n 2 years longer than their sedentary classmates. Another study conducted by Steven Blair, PED, o the Institute o Aerobics Research in Dallas documented the act that a relatively modest amount o exercise has a significant effect on the mortality rate o both men and women. Te higher the fitness level, the lower the death rate (afer the data were adjusted or age differences between subjects in this 8-year investigation o 13,344 individuals). An analysis o the extensive data yielded by both studies suggests one inescapable conclusion: Exercise is medicine! Accepting the premise that regular exercise can play a key role in reducing your risk o medical problems and in decreasing your ultimate costs or health care is critical. Despite the vast number o individuals who lead a sedentary liestyle, the need or and the value o exercising on a regular basis is an irreutable act o lie (and death). For example, afer a detailed review o the results o his long-term investigation, Dr. Paffenbarger concluded that not exercising had the equiva lent impact on a person’s health as smoking one and a hal packs o cigarettes a
Fitness: The Complete Guide
day. Fortunately, with ew exceptions, most people are too sensible to ever consider ravaging their health by smoking excessively. Unortunately, many o these same people ail to recognize the extraordinary benefits o exercise in the prevention o medical problems. Any listing o the medical problems and health-related conditions that can be at least partially treated and controlled by exercise would be ex tensive. Among the most significant o these health concerns and the manner in which exercise is thought to help alleviate each condition are the ollowing: •
Allergies. Exercise is one of the body’s most efficient ways to control nasal congestion (and the accompanying discomfort of restricted nasal blood flow).
•
Angina. Regular aerobic exercise dilates vessels, increasing blood flow — thereby improving the body’s ability to extract oxygen from the bloodstream.
•
Anxiety. Exercise triggers the release of mood-altering chemicals in the brain.
•
Arthritis. By forcing a skeletal joint to move, exercise induces the manufacture of synovial fluid, helps to distribute it over the cartilage, and forces it to circulate throughout the joint space.
•
Back pain. Exercise helps to strengthen the abdominal muscles,the lower back extensor muscles, and the hamstring muscles.
•
Bursitis and tendinitis. Exercise can strengthen the tendons — enabling them to handle greater loads without being injured.
•
Cancer. Exercise helps maintain ideal bodyweight and helps keep body fat to a minimum.
•
Carpal tunnel syndrome. Exercise helps build up the muscles in the wrists and forearms, thereby reducing the stress on arms, elbows, and hands.
•
Cholesterol. Exercise helps to raise HDL (highdensity lipoprotein—the “good” cholesterol) levels in the blood and lower LDL (low-density lipoprotein—the undesirable cholesterol) levels.
•
Constipation. Exercise helps strengthen the abdominal muscles, thereby making it easier to pass a stool.
•
Depression. Exercise helps speed metabolism and deliver more oxygen to the brain; the improved level of circulation in the brain tends to enhance mood.
The Who, What, Why, and How of Personal Training | 5
•
Diabetes. Exercise helps lower blood sugar levels, strengthen the skeletal muscles and heart, improve circulation, and reduce stress.
•
Fatigue. Exercise can help alleviate the fatiguecausing effects of stress, poor circulation and blood oxygenation, bad posture, and poor breathing habits.
•
•
•
•
•
•
Intermittent claudication. Claudication is pain caused by too little blood flow to the extremities. Exercise helps improve peripheral circulation and increases pain tolerance.
•
Glaucoma. Exercise helps relieve intraocular hypertension (the pressure buildup on the eyeball that heralds the onset of glaucoma).
Knee problems. Exercise helps strengthen the structures attendant to the knee (muscles, tendons, and ligaments) thereby facilitating the ability of the knee to withstand stress.
•
Headaches. Exercise helps force the brain to secrete more of the body’s opiate-like, paindampening chemicals (e.g., endorphins and enkephalins).
Lung disease. Exercise helps strengthen the muscles associated with breathing and helps boost the oxygen level in the blood.
•
Memory problems. Exercise helps to improve cognitive ability by increasing the blood and oxygen flow to the brain.
•
Menstrual problems and PMS. Exercise helps to control the hormonal imbalances often associated with PMS by increasing the release of beta-endorphins.
•
Osteoporosis. Exercise promotes bone density, thereby lowering an individual’s risk of experiencing a bone fracture.
•
Overweight problems. Exercise is an appetite suppressant. It also increases metabolic rate, burns fat, increases lean muscle mass, and improves self-esteem—all factors that contribute to healthy weight.
•
Varicose veins. Exercise can help control the level of discomfort caused by existing varicose veins and help prevent additional varicose veins.
Heart disease. Exercise helps promote many changes that collectively lower the risk of heart disease—a decrease in body fat, a decrease in LDL cholesterol, an increase in the efficiency of the heart and lungs, a decrease in blood pressure, and a lowered heart rate. High blood pressure. Exercise reduces the level of stress-related chemicals in the bloodstream that constrict arteries and veins, increases the release of endorphins, raises the level of HDL in the bloodstream, lowers resting heart rate (over time), improves the responsiveness of blood vessels (over time), and helps reduce blood pressure through maintenance of body weight. Insomnia. Exercise helps reduce muscular tension and stress.
International Sports Sciences Association
6 | Introduction
Are the positive effects that result rom exercising regularly worth the required effort? Absolutely. Should you make exercise an integral part o your daily regimen? O course, you should. In countless ways, your lie may depend on it. Te meteoric rise o health care and health problems makes your success as a personal trainer predictable.
Implications for Certified Fitness Trainer Professionals Te need or personal training services continues to grow. As uture ISSA fitness proessionals, it is imperative that we keep up with the evolving recommendations or health and physical fitness that have a direct application or fitness programs and exercise recommendations. With the emergence o the latest technologies, inormation regarding health and fitness is easily accessible. However, because o the nature o the media’s use o vague and brie headlines in conjunction with radio and television sound bites that provide only limited, conusing, and ofen conflicting recommendations, it is important that we can help our clients, riends, and amily members put each new study or report in proper perspective. Personal trainers today are committed to a long-term career in health and fitness and are increasing their knowledge through additional courses in post-rehabilitation, corporate wellness, youth fitness, senior fitness, and preand postnatal specializations to better serve their clients in achieving and living the fitness liestyle. As you can see,
Fitness: The Complete Guide
we as personal trainers have an inherent responsibility to positively influence the health and fitness attitudes o those around us. Individually and collectively, we can bring health and fitness to the masses and make the dream o optimal health a reality or all.
WHAT SHOULD A PERSONAL TRAINER KNOW? As the industry continues to expand its boundaries and the realm o scientific knowledge concerning the human response and adaptation to exercise continues to g row, it is essential that personal fitness trainers be competent in the ollowing: •
Exercise programming
•
Exercise physiology
•
Functional anatomy and biomechanics
•
Assessments and fitness testing
•
Nutrition and weight management
•
Basic emergency procedures and safety
•
Program administration
•
Human behavior and motivation
Our ability as fitness proessionals to educate and effectively draw our clients into the fitness liestyle and optimal health comes rom a plan that is based in the aorementioned areas as well as the knowledge o
The Who, What, Why, and How of Personal Training | 7
muscular, cardiopulmonary, and metabolic adaptations. Tese adaptations are known as the training effect . Te training effect is the body’s adaptation to the learned and expected stress imposed by physical activity. When the body experiences the training effect, it begins to change at the cellular level, allowing more energy to be released with less oxygen. Te heart and capillaries become stronger and more dispersed in order to allow a more efficient flow o oxygen and nutrients. Te muscles, tendons, and bones involved with this activity also strengthen to become more proficient. In time, the body releases unnecessary at rom its rame, and stride and gait become more efficient. Additionally, resting heat rate and blood pressure drop. Tese adaptations can be achieved through an educated trainer who can develop an appropriate fitness and health plan.
individual differences, reversibility, periodization, rest, overtraining, and stimulus variability. Te plan requires a thorough understanding o the major muscles o the body and how they work, as well as an understanding o metabolism—how the body converts ood energy into other orms o energy it can use at rest and during exercise. In addition, trainers must learn about the unction and regulation o the lungs, heart, blood vessels, hormones, brain, and nerves, as well as the weight control and temperature regulation systems at rest and during exercise. Once you have the knowledge and support to develop comprehensive, individualized, and periodized plans that effectively produce the training effect, then you will be able to effectively draw your riends, amily members, and uture clients into the fitness liestyle and optimal health.
Te fitness and health plan must account or the basic principles o fitness training: overload, specificity,
Over a quarter century ago, Dr. Sal Arria and Dr. Fred Hatfield had a vision to pioneer a personal fitness trainer program that would merge in-gym experience with practical and applied sciences in order to share the benefits of the fitness lifestyle with the masses. As the profession continues to grow and expand its boundaries, for the ISSA trainer of today and the ISSA trainer of tomorrow, education and support are vital. It is the hope and vision of the ISSA that through this course text and the support provided by the entire ISSA staff, ISSA-certified trainers will continue to be more educated than in the past; they will be well-rounded and knowledgeable about exercise and how it relates to optimal health and fitness.
International Sports Sciences Association
8 | Introduction
ISSA CODE OF ETHICS AND STANDARDS Principles and Purposes Upon receipt o the ISSA Certificate, members become, in effect, de acto representatives o the leader in the fitness certification industry, and as such are expected to conduct themselves according to the highest standards o honor, ethics, and proessional behavior at all times. Tese principles are intended to aid ISSA members in their goal to provide the highest quality o service possible to their clients and the community.
Academic Standards
6.
Never attempt to treat any health condition or injury under any circumstance whatsoever (except as standard first aid or CPR procedure may require).
7.
Never recommend exercise for anyone with a known medical problem without first obtaining clearance to do so and/or instructions from the attending qualified medical professional.
8.
Ensure that CPR certification and knowledge of first aid procedures is current.
9.
Work toward the ultimate goal of helping clients become more self-sufficient over time, reducing the number of supervised training sessions.
Requirements for Graduation 1.
Certification will not be issued to any student/ member who does not successfully complete or meet all pertinent qualifications or has not achieved passing scores on the relevant ISSA examinations.
2.
Certification will not be issued to any student/ member unless they have successfully completed CPR/AED training as evidenced by a current and valid CPR/AED card.
3.
Certification will not be issued until all fees are paid in full.
Professional Standards ISSA members will do the following: 1.
Serve clients with integrity, competence, objectivity, and impartiality, always putting the clients’ needs, interests, and requests ahead of his or her own. Members must always strive for client satisfaction.
2.
Recognize the value of continuing education by upgrading and improving their knowledge and skills on an annual or semi-annual basis. Members must keep abreast of relevant changes in all aspects of exercise programming theory and techniques.
3.
Not knowingly endanger his or her clients or put his or her clients at risk. Unless they have allied health care licenses, members must stay within the realm of exercise training and lifestyle counseling with clients. Clients with special medical conditions must be referred to proper medical professionals.
4.
Never attempt to diagnose an injury or any other medical or health-related condition.
5.
Never prescribe or dispense any kind of medication whatsoever (including over-thecounter medications) to anyone.
Fitness: The Complete Guide
10. Respect client confidentiality. All client information and records of client cases may not be released without written release from the client. 11. Charge fees that are reasonable, legitimate, and commensurate with services delivered and the responsibility accepted. All additional fees and services must be disclosed to clients in advance. 12. Adhere to the highest standards of accuracy and truth in all dealings with clients, and will not advertise their services in a deceptive manner. 13. Not get intimately involved with their clients. Minimize problems by always maintaining a professional demeanor, not becoming overly friendly with clients, and documenting training sessions, evaluations, and training programs. We cannot overemphasize this point: Be a professional; do not get personally involved with clients! 14. Price cutting (also called low balling) is a sales technique that reduces the retail prices of a service so as to attempt to eliminate competition. It can also potentially eliminate your ability to make a living. Corporate gyms hire trainers with little to no experience and charge members minimally $50 per hour to train with inexperienced trainers. This is a very shortsighted business model that will generally attract the wrong kind of clients. The most effective long-term strategy is to simply charge what you are worth and strive to be the best at what you do.
SECTION ONE
Anatomy and Physiology
Metabolism Basic Anatomy and Physiology Musculoskeletal Anatomy and Physiology
TOPICS COVERED IN THIS UNIT Introduction Homeostasis Understanding Metabolism
Metabolic Set Point Food and Metabolism Environment and Metabolism Exercise and Metabolic Responses Energy Metabolism
ATP Production Monitoring Metabolism Conclusion
UNIT 1
METABOLISM
12 | Unit 1
Unit Outline I. Introduction
IV. Energy Metabolism
II. Homeostasis
A. ATP Production
III. Understanding Metabolism
1. ATP/CP Energy Pathway
A. Metabolic Set Point
2. Glycolytic Pathway
B. Food and Metabolism
3. Oxidative Pathway
C. Environment and Metabolism
4. How the Systems Interact
D. Exercise and Metabolic Responses
5. Glycogen Depletion and Metabolism of Fatigue
1. Aerobic System Changes
B. Monitoring Metabolism
2. Anaerobic System Changes
V. Conclusion
Learning Objectives After completing this unit, you will be able to do the following: •
Define key terms.
•
Understand the role of metabolism in the body and how it relates to exercise.
•
Determine the metabolic needs of each of the three energy pathways described, and apply them in the coming units.
INTRODUCTION
training effect: An increase in functional capacity of muscles and other bodily tissues as a result of increased stress (overload) placed upon them. homeostasis: The automatic tendency to maintain a relatively constant internal environment.
Fitness: The Complete Guide
As revealed in the book’s introduction, personal fitness trainers have a tremendous influence on shaping the health and fitness attitudes and practices o those around them. Te sphere o influence includes riends, amily members, coworkers, and, o course, clients. As a fitness proessional, your ability to effectively draw your clients into the fitness liestyle—including the ability to maintain optimal health—largely depends on your knowledge o the muscular, cardiopulmonary, and metabolic adaptations to exercise. Tese adaptations are known as the training effect. Te training effect impacts the body in several ways. Te body begins to change at the cellular level, allowing more energy to be released with less oxygen. Heart unction improves and the capillaries prolierate in order to allow a more efficient flow o oxygen and nutrients. Te muscles, connective tissues, and bones involved with a particular physical activity strengthen to accommodate improved proficiency at perorming the activity. Over time, the body’s composition changes (e.g., at mass may increase while muscle mass decreases) and movements become more efficient. In addition, resting heart rate and blood pressure drop. You can help your clients achieve these adaptations by educating yoursel and learning how to develop appropriate fitness and health plans or them.
Metabolism | 13
Te training effect would not be possible without sufficient energy to bring about the positive muscular, cardiopulmonary, and metabolic adaptations. But where exactly does this energy come rom?
Thermostat activated
Where Does Energy Come From? All energy on ear th originates rom the sun. Plants use the light energy rom the sun to orm carbohydrates, ats, and proteins. Carbohydrates are sugars and starches used by the body as uel. Fats are compounds that store energy. Proteins are important components o cells and tissues; they are large, complex molecules comprised o amino acids. (Carbohydrates, ats, and proteins are discussed in more detail in Section 5 o this text.) Humans and other animals eat plants and other animals to obtain energy required to maintain cellular activities. Te body uses carbohydrates, ats, and proteins to provide the necessary energy to maintain cellular activity both at rest and during activity. Because all cells require energy, the body must have a way to convert carbohydrates, ats, and proteins into a biologically usable orm o energy to both uel physical activity a nd provide the structura l components o the body. Te ability to run, jump, and lif weights is contingent upon, and limited by, the body’s ability to transorm ood into biological energy. Tese physical abilities are urther contingent upon thousands o chemical reactions that occur throughout the body all day long. Collectively, these reactions are known as metabolism. Tese many chemical reactions occurring in the body must be regulated in order to maintain a balance. Te body consists o trillions o cells, which are organized into tissues, organs, and systems. Tis intricate organized system is covered in more detail in Unit 2. Te body’s components work together in a highly organized manner to maintain th is balance. Metabolic activities are continually occurring i n the tril lions o cells in your body and must be careully regulated to maintain a constant internal environment, or steady state. Tis steady state must be maintained regardless o your ever-changing external environment.
HOMEOSTASIS Homeostasis reers to the body’s automatic tendency
to maintain a constant internal body environment through various processes. Walter Bradord Cannon is credited with coining the term in his book Te Wisdom of the Body (1932). For homeostasis to work, eedback systems must exist that various physiological u nctions turn off and on. Imagine a eedback system such as the thermostat in your urnace or air conditioning system. I
Room condition warms up
Room condition returns to normal
Room condition returns to normal
Room condition cools down
Thermostat activated
Figure 1.1 Homeostasis example
the temperature increases above the set point determined by the system, then the thermostat shuts off the urnace. In this way, the temperature is kept at the desired steady state. I the temperature decreases below the set point determined by the system, then the thermostat turns on the urnace to maintain the desired steady state (see Figure 1.1). Tis eedback system revolves around a cycle o events. Inormation about a change is ed back to the system so that the regulator (in this exa mple, the thermostat) can control the process (in the example o temperature regulation). A good example o homeostasis in the body is the method by which the body maintains a constant temperature o 98.6 degrees Fahrenheit. For example, i either physical exertion or external heat causes your body temperature to rise, your brain sends a signal to increase the rate o sweating. Heat is carried away in sweat, which evaporates. I body temperature begins to drop due to a cold external
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environment, shivering begins to generate heat and keep the body temperature at that critical 98.6 degrees F. Other metabolic unctions under homeostatic control include the ollowing: •
Hormone production and concentration level maintenance
•
Maintenance of serum oxygen levels and carbon dioxide levels
•
pH balance in the blood and cells
•
Water content of cells and blood
•
Blood glucose levels and other nutrient levels in the cell
•
Metabolic rate
glucose: Principal circulating sugar in the blood and the major energy source of the body.
Te concept o homeostasis is o special interest to fitness enthusiasts. You are in equilibrium even with environmental stimuli acting upon you. For example, think about how your muscles change in response to different training programs. I you spend most o your time lifing heavy weights, your muscles will grow larger; a shif in your homeostasis takes place. Te simple action o weight training causes more protein synthesis in the target muscles. Hormone levels change to accommodate this growth. On the other hand, i you choose to run several miles per day, your muscles will adapt differently. Tey develop a higher endurance capacity, they stimulate the ormation o more at-burning, slow-twitch muscle fibers, and they develop a higher capacity to use oxygen in energy production. Nutrient intake can also affect your homeostatic balance. Eating too much o the wrong oods or too little o the right oods can cause homeostasis to shif out o balance. Consume too many calories, and your body stores at; too little protein, and your muscles break down. I you don’t consume enough energy-supplying calories, you will eel tired sooner. For optimum homeostasis and metabolism, eating the right nutrients in the right amounts at the right times is vital.
ketone bodies: Bodies produced as intermediate products of fat metabolism.
UNDERSTANDING METABOLISM
metabolism: The total of all the chemical and physical processes by which the body builds and maintains itself (anabolism) and by which it breaks down its substances for the production of energy (catabolism).
lactic acid: A by-product of glucose and glycogen metabolism in anaerobic muscle energetics. amino acid: The building blocks of protein. There are 24 amino acids, which form countless number of different proteins. fatty acids: Any of a large group of monobasic acids, especially those found in animal and vegetable fats and oils.
Te body sustains itsel and adapts to its environment through metabolism . In order or metabolism to occur, the body needs both energy and building blocks or growth and repair. It gets its energy rom the breakdown o nutrients such as glucose, ketone bodies, lactic acid, amino acids , and fatty acids. o construct molecules or growth and repair, a delicate interplay must exist between anabolism and catabolism. Te many biochemical processes that make up the body’s metabolism are categorized into two general phases: anabolism and catabolism. Anabolism and catabolism occur simultaneously—and constantly. However, they differ in magnitude depending on the level o activity or rest and on when the last meal was eaten. When anabolism exceeds catabolism, net growth occurs. When catabolism exceeds anabolism, the body has a net loss o substances and body tissues and may lose weight.
anabolism: The building up in the body of complex chemical compounds from simpler compounds (e.g., proteins from amino acids).
Anabolism includes the chemical reactions that combine different biomolecules to create larger, more complex ones. Te net result o anabolism is the creation o new cellular material, such as enzy mes, proteins, cell membranes, new cells, and growth/ repair o the many tissues. Tat energy is stored as glycogen and/or at and in muscle tissue. Anabolism is necessary or growth, maintenance, and repair o tissues.
catabolism: The breaking down in the body of complex chemical compounds into simpler ones (e.g., proteins to amino acids).
Catabolism includes the chemical reactions that break down complex biomolecules into simpler ones or energy production, or recycling o molecular components, or or their excretion. Catabolism provides the energy needed or transmitting nerve impulses and muscle contraction.
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Metabolism | 15
Metabolism includes only the chemical changes that occur within tissue cells in the body. It does not include those changes to substances that take place in the digestion o oods in the gastrointestinal system. For optimal unction, a healthy metabolism needs many nutrients. A slight deficiency o even one vitamin can slow down metabolism and cause chaos throughout the body. Te body builds thousands o enzymes to drive its metabolism in the direction influenced by activity and nutrition. So, when you are training or engaged in vigorous physical activity several hours a day, you must ensure that your diet contains the nutrients your body needs in order to optimize the many metabolic unctions taking place.
METABOLIC SET POINT Based on the discussion o homeostasis and metabolism, it is evident that the body is a highly regulated collection o many biochemical reactions. Much research over the years has revealed that the body seeks to maintain a cer tain base rate o metabolism, called the metabolic set point, which results in basal metabolic rate (BMR). Tis set point is regulated by both genetic and environmental actors. Researchers have demonstrated that you can change your metabolic set point through diet and physical act ivity. Te metabolic set point is the average rate at which the metabolism runs, and it will result in a body composition set point. People with a slow metabolism seem to store at easily, while people with a ast metabolism seem to be able to eat and never gain at. Your metabolic set point can be influenced by the external environment (climate), nutrition, exercise, and other actors. Studies have demonstrated that when individuals go on a low-calorie diet, the body’s metabolic set point becomes lower in order to conserve energy. It actually resets itsel to burn ewer calories, thereby conserving energy. Exercise tends to increase metabolic rate, causing the body to burn more at or energy.
Calculating Caloric Expenditure You can estimate your total daily caloric expenditure by multiplying the HarrisBenedict equations or basal metabolic rate by an activity level actor that accounts or your daily physical activity levels and t he thermic effect o ood.
metabolic set point: The base rate of metabolism that the body seeks to maintain; resulting in basal metabolic rate. basal metabolic rate (BMR): The minimum energy required to maintain the body’s life function at rest; usually expressed in calories per hour per square meter of the body surface.
thermic effect: The heat liberated from a particular food; it is a measure of its energy content and its tendency to be burned as heat. This process of heat liberation is also commonly referred to as “thermogenesis.”
Calculating Caloric Expenditure MALE FEMALE
metric: DCE = ALF × ((13.75 × WKG) + (5 × HC) – (6.76 × age) + 66) imperial: DCE = ALF × ((6.25 × WP) + (12.7 × HI) – (6.76 × age) + 66) metric: DCE = ALF × ((9.56 × WKG) + (1.85 × HC) – (4.68 × age) + 655) imperial: DCE = ALF × ((4.35 × WP) + (4.7 × HI) – (4.68 × age) + 655)
WHERE ALF = Activity level factor
AND ALF HAS THE FOLLOWING VALUES:
DCE = Daily caloric expenditure
Sedentary:
ALF = 1.2
HC = Height in centimeters
Lightly active:
ALF = 1.375
HI = Height in inches
Moderately active:
ALF = 1.55
WKG = Weight in kilograms
Very active:
ALF = 1.725
WP = Weight in pounds
Extremely active:
ALF = 1.9
Eq. 1.1
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calorie: A unit of heat; specifically, it is the amount of energy required to raise the temperature of 1 kilogram of water 1 degree Celsius at 1 atmosphere. As a unit of metabolism (as in diet and energy expenditure), it is spelled with a capital C; 1 Calorie = 1,000 calories, or 1kilocalorie (kcal). kilocalorie (kcal): A unit of measurement that equals 1,000 calories, or 1 Calorie. Used in metabolic studies, it is the amount of heat required to raise the temperature of 1 kilogram of water 1 degree Celsius at a pressure of 1 atmosphere. The term is used in nutrition to express the fuel (energy) value of food.
respiratory quotient (RQ): A method of determining the “fuel mix” being used, giving us a way to measure the relative amounts of fats, carbohydrates, and proteins being burned for energy.
FOOD AND METABOLISM In addition to exercise, the type o ood you eat can also influence your metabolism. Te ood you eat can be burned to liberate energy, it can be converted into body weight, or it can be excreted. All oods release heat when they are burned. Tis release o heat is measured in kilocalories. A calorie is a unit o heat. Practically speaking, this unit is too small to be useul, thereore, the kilocalorie (1,000 calories) is the preerred unit in metabolism studies. Te term Calorie (with a capital “C”) is synonymous w ith ki localorie. Te heat liberated rom ood is known as the thermic effect. Increased thermogenesis (heat production) correlates with increased oxygen consumption and an increased metabolic rate. Te more heat your body produces, the more oxygen it needs, because heat cannot be liberated in the absence o oxygen. Food efficiency is simply a measure o how efficiently a particular ood is converted to body weight. Foods with high ood efficiency are prone to be converted to body weight, while oods with low ood efficiency are prone to be burned as energy. Understanding how the body will use the consumed calories can help you in setting up your nutritional program. Simply counting calories will not lead to loss o body at. Te heat liberated rom a particular ood, whether it is at, protein, or carbohydrate, is determined by its particular molecular structure, and this structure determines its thermic effect. Te higher the thermic effect o any par ticular ood, the higher the metabolic rate will be. Know what the body is consuming; and, more importantly, know how the body will use the consumed calories. A method o determining the mix o uels being utilized in the body is ca lled the respiratory quotient (RQ), which provides a way to measure the relative amounts o ats, carbohydrates, and proteins being burned or energy. Te respiratory quotient (RQ) is the ratio o the volume o carbon dioxide expired to the volume o oxygen consumed. Because the amounts o oxygen used up or the combustion o at, carbohydrate, and protein differ, differences in the RQ indicate which nutrient source is being predominantly used or energy purposes. Te ormula or calculating RQ is as ollows:
RQ = volume of CO2 expired ÷ volume of O2 utilized Eq. 1.2
oxidation: The chemical act of combining with oxygen or of removing hydrogen.
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Te RQ or carbohydrate is 1.0, whereas the RQ or at is 0.7. Fat has a lower RQ value because atty acids require more oxygen or oxidation than the amount o carbon dioxide produced. Te RQ or energy production rom protein is about 0.8. Te average person at rest will have an RQ o about 0.8; however, this result is rom using a mixture o atty acids and carbohydrates, not the protein itsel, or energy production. Remember, proteins (broken down into amino acids) are not usually used or energy. In a normal diet containing carbohydrate, at, and protein, about 40to 45 percent o the energy is derived rom atty acids, 40 to 45 percent rom carbohydrates, and 10 to 15 percent rom protein. However, this rate o energy production varies based on diet, physical activity, and level o physical training.
Metabolism | 17
Research indicates that when the diet is high in carbohydrates, the RQ is higher, thereore more energy is being produced rom carbohydrates. When the diet is low in carbohydrates and high in at, more energy is produced rom at. Interestingly, recent studies published in academic journals suggest that more efficient body at reduction occurs with a high-at diet than with a high-carbohydrate diet (on a calorie-percalorie basis). In addition, training intensity affects the energy source during exercise. For example, • a training intensity below 60 percent o maximal oxygen uptake (VO2 max) results in a RQ o about 0.8, indicating an equal portion o energy derived rom atty acids • and carbohydrate. As training intensity increases above 60 percent o VO2 max, more • carbohydrate is used or energy. Exercise intensity at 100 percent VO2 max (which can only be sustained or minutes) yields a RQ o 1. Keep in mind that amino acids, in particular the branched-chain amino acids (BCAAs, which aid in recovery), are also being used or energy during exercise and at rest, perhaps as much as 10 percent or more during exercise. In general, physical conditioning lowers the RQ, which means more energy is being obtained rom atty acids in the trained individual. However, more energy is also being obtained rom protein in the trained individual. Carbohydrate is always being used or energy. For example, in a study comparing the RQ o untrained versus trained individuals during exercise, the RQ o the untrained individuals was 0.95 and the RQ o the trained individuals was 0.9. Tis means that while both groups were using mostly carbohydrate or uel during exercise, the trained individuals were using a higher amount o atty acids or energy. At rest, atty acids are the predominant energy source in most people; as exercise begins, carbohydrate utilization increases. High-intensity exercise uses more carbohydrate, while low- to moderate-intensity exercise uses atty acids and carbohydrate or energy. O course, these ratios change when one consumes only ats and proteins and no carbohydrates as uel.
maximal oxygen uptake • (VO2 max): The highest rate of oxygen consumption which a person is capable. branched-chain amino acids (BCAAs): The amino acids L-leucine, L-isoleucine and L-valine, which have a particular molecular structure that gives them their name and comprises 35 percent of muscle tissue. The BCAAs, particularly L-leucine, help increase work capacity by stimulating production of insulin, the hormone that opens muscle cells to glucose. BCAAs are burned as fuel during highly intense training and at the end of long-distance events when the body recruits protein for as much as 20 percent of its energy needs.
While this discussion o RQ is very brie, you can see that the energy substrate utilization o the body is quite varied, and both composition o the diet and intensity o physical activity determine which energy substrates are used. Tereore, it is easy to see why different sports require different dietary considerations.
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ENVIRONMENT AND METABOLISM Te body’s environment also influences its metabolic rate. When you are exposed to a progressively colder climate, your body will increase its metabolic rate to keep the body temperature constant and to prevent shivering. Shivering is invoked when the core temperature o the body begins to drop rom being in the cold. Shivering is actually a series o involuntary muscle contractions that are triggered to create heat in the body, like turning on a urnace. When exposed to higher-than-average cold conditions or a ew days, the body actually increases its basal metabolic rate; its goal is to run hotter than average in order to compensate or being in a colder climate. When conditions begin to warm up, even a 60-degreeFahrenheit (F) day can seem extremely hot, because the body’s metabolic rate is already run ning ast. Afer several days o acclimating to the hot climate, the metabolic rate decreases and 80 degrees F eels as hot as the 60 degrees F did a ew months earlier.
EXERCISE AND METABOLIC RESPONSES Exercise stimulates a series o metabolic responses that affect the body’s anatomy, physiology, and biochemical makeup. Endurance exercise stimulates the following changes: •
Increased muscle glycogen storage capacity
•
Increased muscle mitochondrial density
•
Increased resting adenosine triphosphate (ATP) content in muscles
•
Increased resting creatine phosphate (CP) content in muscles
•
Increased resting creatine content in muscles
•
Increased aerobic enzymes
•
Increased percentage of slow-twitch muscle fibers
•
Decreased percentage of fast-twitch muscle fibers
•
Decreased muscle size, when compared to strength training
•
Increased cardiac output
•
Decreased resting heart rate
•
Decreased body fat
•
Increased Krebs cycle enzymes
•
Increased number of capillaries
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Te magnitude o these changes is driven primarily by whether the exercise is anaerobic or aerobic. Te type and duration o exercise dictates the primar y energy mix used. High-intensity exercise simulates development o asttwitch muscle fibers, while low-intensity exercise results in development o slow-twitch muscle fibers. In addition, a series o hormonal changes occur during exercise and non-exercise periods. Tese changes also are benefited and acilitated with a nutrient profile that matches the type o metabolic fluctuation.
Aerobic System Changes Aerobic training greatly increases the body’s unctional capacity to transport and use oxygen and to burn atty acids during exercise. Recent research shows that long, slow distance training is not as efficient as interval training in acilitating this unctional capacity. Some o the major changes measured as a result o aerobic exercise (especially interval training) include the ollowing: •
Increased mitochondrial density in slow-twitch muscle fiber, which results in higher energy production from fatty acids. Maximum oxidative capacity develops in all fiber types
•
Higher aerobic capacity
•
Increase in trained muscle capacity to utilize and mobilize fat, resulting from higher amounts of fat-metabolizing enzymes, and increased blood flow
•
Greater development of slow-twitch muscle fibers, increased myoglobin content (an iron–protein compound in muscle), which acts to store and transport oxygen in the muscles
Metabolism | 19
Anaerobic System Changes Anaerobic training greatly increases the body’s unctional capacity or development o explosive strength and maximization o short-term energy systems. Some o the major changes measured as a result o anaerobic exercise include the ollowing: •
Increased size and number of fast-twitch muscle fibers
•
Increased tolerance to higher levels of blood lactate
•
Increases in enzymes involved in the anaerobic phase of glucose breakdown (glycolysis)
•
Increased muscle resting levels of ATP, CP, creatine, and glycogen content
•
Increased levels of growth hormone and testosterone after short bouts (45 to 75 min) of high-intensity weight training
adenosine triphosphate (ATP): An organic compound found in muscle which, upon being broken down enzymatically, yields energy for muscle contraction. creatine phosphate (CP): A high-energy phosphate molecule that is stored in cells and can be used to immediately resynthesize ATP.
ENERGY METABOLISM Energy metabolism is a series o chemical reactions that result in the breakdown o oodstuffs (carbohydrate, at, protein) by which energy is produced, used, and given off as heat. Roughly, the body is about 20 percent efficient at trapping energy released. About 80 percent is released as heat, which explains why your body heats up quickly when you exercise. A closer look at muscle anatomy reveals that the mode o energy storage and energy systems used is related to physical activity. Physical activities can be classified into these our basic groups, based on the energy systems that are used to support these activities: •
Strength/power: Energy coming from immediate ATP stores. Examples include shot put, powerlift, high jump, golf swing, tennis serve, and a throw. Activities last about 0 to 3 seconds of maximal effort.
•
Sustained power: Energy coming from immediate ATP and CP stores. Examples include sprints, fast breaks, football lineman. Activities last about 0 to 10 seconds of near-maximal effort.
•
Anaerobic power/endurance: Energy coming from ATP, CP, and lactic acid. Examples include 200- to 400-meter dash and 100-yard swim. Activities lasting about 1 to 2 minutes.
•
Aerobic endurance: Energy coming from the oxidative pathway. Activities last over 2 minutes.
In power events, which last a ew seconds or less at maximal effort, the muscles depend on the immediate energy system, namely AP and CP reserves. In speed events, the immediate and non-oxidative (glycolytic) energy sources are utilized. In endurance events, the immediate and non-oxidative energy sources are used, and the oxidative energy mechanisms become a more important source o energy. AP and CP are replenished rom energy derived rom complete breakdown o glucose, atty acids, and some proteins.
ATP PRODUCTION Adenosine triphosphate (AP) is the molecule that stores energy in a orm that can be used or muscle contractions. Energy production then revolves around rebuilding AP molecules afer they are broken down or energy utilization. Muscle cells store a limited amount o AP. During exercise the body requires a constant supply o AP in
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order to provide the energy needed or muscular contraction. Tereore, to maintain a constant supply o energy, metabolic pathways must exist in the cell with the ability to produce AP rapidly. Muscle cells can produce AP by any one o or a combination o three metabolic pathways: the AP/CP pathway, the glycolytic pathway, and the oxidative pathway.
ATP/CP Energy Pathway ATP/CP pathway: ATP and CP provide anaerobic sources of phosphate-bond energy. The energy liberated from hydrolysis (splitting) of CP re-bonds ADP and Pi to form ATP.
Creatine phosphate (CP) is high-energy phosphate molecule that is stored in cells and can be used to immediately re-synthesize AP. Te ATP/CP pathway (see Figure 1.2) is anaerobic, which means it requires no oxygen or energy use. Tis energy pathway is demonstrated in sports that require ballistic, explosive strength or maximal effort or short periods o time, such as shot putting, pitching, weight lifing, and powerlifing. AP is the energy source or all human movement. Te release o one o its three phosphate molecules provides the energy or human movement. Unortunately, muscle cells store only a limited supply o AP that is readily available or use (5 mmol/kg o muscle). In maximal efforts, it is totally gone within 1.26 seconds! However, regardless o their intensity or length, all activities begin with this pathway. With the help o an enzyme called myosin APase, AP loses one phosphate molecule in order to release energy (see Equation 1.3).
ATP
myosin ATPase
ADP + Pi + Energy Pi: inorganic phosphate
Eq. 1.3
ADP + Pi is resynthesized into Pi ATP CP from muscle lends a phosphate (Pi) to ADP ADP
ATP losses phosphate to release energy Energy for muscle contraction
Figure 1.2 The ATP/CP energy pathway
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Metabolism | 21
For short-term, high-intensity activities such as shot putting or throwing, this pathway is enough. However, urther use in this pathway requires that the adenosine diphosphate (ADP; di = the two phosphate molecules lef afer one is lost) be resynthesized back to AP with the help o creatine phosphate (CP) and an enzyme called creatine kinase (see Equation 1.4).
ADP + CP
Creatine Kinase
ATP + Creatine
adenosine diphosphate (ADP): an organic compound in metabolism that functions in the transfer of energy during the catabolism of glucose, formed by the removal of a phosphate molecule from adenosine triphosphate (ATP) and composed of adenine, ribose, and two phosphate groups.
Eq. 1.4
Like AP, CP is stored in small amounts (16 mmols/kg o muscle). As seen in Figure 1.3, CP stores all rapidly afer 10 seconds o maximal activity and are usually completely depleted in under 60 seconds. Whether or not you can increase your resting levels o AP through training has not widely been studied or understood. Research has suggested that it is possible through both weight training and aerobic training. However, this possibility is mainly because o fiber hypertrophy (increase in size), thus more AP can be stored in type II than in type I muscle fibers (considering the size and growth potential o type II fibers). Perhaps an even bigger question than “how much?” or “can you increase?” is “how quickly can AP and CP stores be replenished?” Although individual differences exist, research has shown that AP stores can be ully restored within 3.5 minutes and CP stores can be ully replenished within 8 minutes.
type II muscle fibers (fast twitch): Muscle fiber type that contracts quickly and is used mostly in intensive, short-duration exercises. type I muscle fibers (slow twitch): A muscle fiber characterized by its slow speed of contraction and a high capacity for aerobic glycolysis.
CP-Splitting
Glycolysis Oxidation
y l p p u S y g r e n E f o t n e c r e P
Time in Seconds Figure 1.3 Pathways of muscular energetics
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Glycolytic Pathway glycolytic pathway: A metabolic process in which glucose is broken down to produce energy anaerobically. gluconeogenesis: Chemical process that converts lactate and pyruvate back into glucose. When glycogen (sugar stored in muscles) stores are low, glucose for emergency energy is synthesized from protein and the glycerol portion of fat molecules. This is one important reason that ATP/CP athletes and glycolytic athletes are warned to stay away from undue aerobic exercise: It’s muscle-wasting. anaerobic threshold: The point where increasing energy demands of exercise cannot be met by the use of oxygen, and an oxygen debt begins to be incurred. oxidative pathway: A metabolic process in which oxygen combines with lactic acid, resynthesizing glycogen to produce energy aerobically. Krebs cycle: Citric acid cycle; a set of 8 reactions, arranged in a cycle, in which free energy is recovered in the form of ATP. electron transport chain: The passing of electrons over a membrane, aiding in a reaction to recover free energy for the synthesis of ATP.
Like the AP/CP pathway, the glycolytic pathway is anaerobic. Once it has depleted the readily available AP/CP stores, the body must break down carbohydrates to produce more AP. Tis process uses either glycogen (which is stored in the muscle cells) or glucose (which is ound in the blood) to convert ADP back into AP; the waste product is lactic acid (see Equation 1.5).
Glucose + 2Pi + 2ADP + 2NAD+
2 lactic acid + 2ATP + 2NAD
Eq. 1.5
Tis lactic acid eventually builds more quickly than it can be flushed out o the muscle to the point o the anaerobic threshold, otherwise known as muscular atigue. At this point, the body must either stop or slow down until the lactic acid is removed. Lactic acid is converted to a less toxic orm, called lactate, which is used either as an energy substrate or to produce more glucose (a process called gluconeogenesis). Getting rid o lactic acid is not as important as it is how efficiently the body can use it. I you produce lactic acid aster than you can use it, therein lies the problem. Stored sugars are rarely ever depleted (and are never depleted in the glycolytic pathway). However, this is not the limiting actor; the limiting actor is the accumulation o lactic acid. Generally, the glycolytic pathway ends under maximal conditions at around 80 seconds beore the oxidative pathway (and lower levels o activity) takes over. How well muscles function in the glycolytic pathway is determined by three related factors: •
How quickly the body can utilize the lactic acid
•
How well the body can tolerate the pain caused by the accumulation of lactic acid
•
How far the body can go before it becomes vital to clear the lactic acid in order for work to continue. This is called the anaerobic threshold.
pyruvate: A byproduct of glycolysis.
Blood lactate levels usually return to normal within a n hour afer activity. Research shows that training can increase the rate in which lactic acid is utilized or removed as well as push back the anaerobic threshold. As or the ability to tolerate the pain, it comes with personal experience.
beta oxidation: A series of reactions in which fatty acids are broken down.
Oxidative Pathway Te oxidative pathway is a system that is aerobic, which means it uses oxygen to produce AP by way o the Krebs cycle and electron transport chain. Ultimately, more AP is produced through this pathway than through the other two; however, it takes much longer. Pyruvate, which is produced through glycolysis, undergoes a long trip through the Krebs cycle to convert several coenzymes that have lost an electron back into their original state. It is in the electron transport chain where these coenzymes undergo oxidation to convert ADP back into AP. In the end, up to 38 molecules o AP can be produced through the oxidative pathway. It is only in this pathway that at can be used or energy. Breaking down at or energy is also a long process (called beta oxidation), which does not direct ly produce AP.
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Metabolism | 23
Rather, it provides the coenzymes needed or the Krebs cycle. Scientists have estimated that while at rest (and in the oxidative pathway), 70 percent o energy comes rom at, not carbohydrates or protein. However, as exercise intensity increases, more and more carbohydrates are used instead o at (beta oxidation can’t keep up). In act, at the upper limits o the aerobic pathway, 100 percent o the energy is coming rom carbohydrates—not at! I at these levels carbohydrates aren’t available, the body will indeed catabolize the very muscle it’s using or energy.
How the Systems Interact o better understand how each o these energy systems relate to each other, you need to take a look at what happens when muscles contract. First, consider the immediate energy systems. Te brain sends a signal along the nerves, triggering a release o calcium ions in the muscles, which stimulates the muscles to contract and, in the process, the high-energy molecule AP releases energy and is reduced to ADP plus one phosphate
Contraction Blood ADP + Pi
Creatine phosphate
Creatine
ATP
Myosin ATPase
Ca-ATPase
Relaxation
Amino acids
Glycogen Glucose
Oxidative phosphorylation
Glycolysis
Lactic acid
Proteins
Fatty acids
Oxygen
Fatty acids MUSCLE FIBER Figure 1.4 Pathway interactions
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atom. In this way, the immediately available AP stores are depleted very rapidly, in the first ew seconds o a maximal muscle contraction. Te second immediate source o cellular energy is creatine phosphate (CP). Te cell contains several more times CP molecules than AP molecules. Creatine phosphate serves to instantaneously regenerate AP molecules. Tereore, the AP that is broken down to ADP during muscle contraction is restored to the high-energy AP by CP. Te third immediate energy system enables the cell to regenerate AP rom two ADP molecules, resulting in one AP and one adenosine monophosphate (AMP) molecule. Tis immediate energy source is depleted in a matter o seconds under conditions o all-out effort (maximal muscle contractions). Te storage capacity o AP and CP in a cell is quickly reached or a particular muscle size. In order to increase the amount o AP and CP on hand, the muscle fibers must increase in size. Tis is why power athletes get big muscles. Te workload demands that more AP and CP be available. o meet this demand, the muscle fibers increase in size, causing the entire muscle to get big. When you train, different energy systems are conditioned to work best at the particular workload imposed on the muscles. As the immediate energy supply is quickly depleted through high-intensity physical activity, the non-oxidative energy source kicks in. Te non-oxidative system is a major contributor o energy during 4 to 50 seconds o effort. Non-oxidative metabolism (glycolysis) involves the breakdown o glucose to regenerate A DP into AP. Muscle tissue is densely packed with non-oxidative enzyme systems. What happens chemically is that the glucose molecule is split in hal and energy is released. Tis energy is enough to regenerate 2 AP molecules and leave two
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pyruvate molecules. In general, these pyruvate molecules are immediately converted to lactic acid molecules. Te amount o ree glucose is generally low in the cells, so glucose is derived rom the breakdown o glycogen. Fast-twitch muscle fibers (those associated with strength and size) are also reerred to as ast glycolytic muscle fibers, because they house the metabolic machinery to get quick energy through ast glycolysis pathways. Te asttwitch fibers have a low capacity or oxidative metabolism and are instead set up to ru n glucose through their ast glycolysis pathways. Lactic acid then builds up because it is being produced too rapidly to enter into the oxidative pathways. Lactic acid is then cleared rom the muscle, ed into the bloodstream, taken to the liver, and there made into glucose and glycogen. Glycolysis takes place in the cytoplasm o the cell. For physical activities lasting more than 2 minutes, the oxidative metabolic pathways produce the majority o energy to maintain muscle contractions. Potential oxidative energy sources include glucose, glycogen, ats, and amino acids. Oxidative energy production takes place in the mitochondria o the cells. Far more energy is produced when glucose is completely broken down in the mitochondria. Glucose is still first split in hal by glycolysis. Te pyruvate molecules then enter into the mitochondria, where they are completely broken down. Te oxidative pathways are the Krebs cycle and electron transport. Fatty acids, which come rom at, are a major energy source during endurance events. Te processes o at utilization are activated more slowly than carbohydrate metabolism and proceed at a lower rate. Fatty acids are activated and combined with the molecule carnitine, which enables them to then be transported into the mitochondria.
Metabolism | 25
Glycogen Depletion and Metabolism of Fatigue Glycogen is essential to perormance or both anaerobic and aerobic activities. Muscles being strenuously exercised will rely on glycogen to power these strength-generating muscle contractions. In endurance exercise, while the primary uel is atty acids, glycogen is also utilized. In act, at catabolism works better when carbohydrates are being metabolized. Studies on long-term exercise and work perormance all indicate the onset o atigue when glycogen is depleted. Tis again underscores the importance o adequate carbohydrate intake and glycogen replenishment. Glycogen depletion is just one actor that contributes to the onset o atigue. Several other atiguecausing actors acing athletes include the ollowing: •
ATP and CP depletion
•
Lactic acid accumulation
•
Calcium ion buildup in muscles
•
Oxygen depletion
•
Blood pH decrease
MONITORING METABOLISM Until recently, there were no affordable and easy-to-use home testing methods that were designed or athletes to measure key metabolic parameters. Measuring the state o nitrogen metabolism allows you to determine whether protein intake is sufficient and also whether certain supplements are being ingested in a mounts that are sufficient or improving nitrogen balance. Currently on the horizon is a newly developed testing device that combines nitrogen balance testing with at metabolism status. Tese tests measure the output o metabolic waste products in uri ne. Tey are easy to use a nd offer a means to finely tune your train ing and nutrition programs. A product developed by B. Fritz and Dr. Fahey is a testing method that was probably the best-kept secret o Russian athletes. Tis test provides an economical way to determine testosterone and cortisol levels in the body by analysis o saliva. When t he body is over trained, cortisol levels increase. Cortisol is a catabolic hormone that stimulates the breakdown o muscle tissue. High amounts in the blood ultimately lead to tissue wasting and negative nitrogen balance. So, when the testosterone/cortisol
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26 | Unit 1
ratio is high, anabolism is prevailing. However, when cortisol levels are high and the ratio is lowered, it is an indication o overtraining. esting testosterone/cortisol ratio helps you determine whether the body is in a state o overtraining or not. In this way, you can determine how hard to train, whether to take a ew days off, or i tra ining intensity should increase.
resting metabolic rate (RMR): The amount of energy (calories) required to efficiently perform vital bodily functions such as respiration, organ function and heart rate while the body is awake, but at rest.
In addition, in the medical field and in many fitness centers, handheld portable • indirect calorimeters are used that measure oxygen consumption ( VO2) and determine resting metabolic rate (RMR). As discussed earlier in this unit, the rate o oxidation or the burning o the calories is different or at, carbohydrate, and protein. Te ood you eat can either be burned to liberate energy, converted into body weight, or be excreted. I you light a candle and then place a dome over the candle, cutting off the fire’s source o oxygen, the fire will go out. In the same way the body’s ability to undergo oxidation is contingent on oxygen. I the body is getting more oxygen, it should be burning more calories. Nutrition monitoring plays a vital role in the care o patients with diabetes, heart disease, high blood pressure, and obesity, as well as conditions that place patients at risk or malnutrition, such as cancer, burns, trauma, inection, obstructive lung disease, and HIV. Indirect calorimeters can be used in acute care, long-term care, home care, and clinic-based care settings such as physician offices, rehabilitation centers, ambulatory surgery centers, and fitness-based acilities.
CONCLUSION In order to maintain its many chemical and physical activities, the body needs energy. Earth’s energy originates rom the sun. Plants use solar energy to perorm chemical reactions to orm carbohydrates, at, and protein. Humans, like other animals, consume plants and other animals to obtain the energy required to maintain cellular activities. Tese cellular activities, k nown as metabolism, are maintained under homeostatic controls. Te many chemical reactions occurring in the body must be regulated in order to maintain a balance between the trillions o cells in the body. Tese cells maintain balance through an intricate organization system. We will now discuss this intricate organized system known as the body.
Fitness: The Complete Guide
Metabolism | 27
Key Terms adenosine diphosphate (ADP)
electron transport chain
metabolism
adenosine triphosphate (ATP)
fatty acids
oxidation
amino acid
gluconeogenesis
oxidative pathway
anabolism
glucose
pyruvate
anaerobic threshold
glycolytic pathway
respiratory quotient (RQ)
ATP/CP pathway
homeostasis
resting metabolic rate (RMR)
basal metabolic rate (BMR)
ketone bodies
thermic effect
beta oxidation
kilocalorie (kcal)
training effect
branched-chain amino acids (BCAAs)
Krebs cycle
type I muscle fibers (slow twitch)
calorie catabolism
lactic acid •
maximal oxygen uptake ( VO2 max)
type II muscle fibers (fast twitch)
metabolic set point
creatine phosphate (CP)
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