Why Exercise Is Essential 9781621319993, 1621319997

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Why Exercise is Essential First Edition

By Jeff Schlicht Western Connecticut State University

Bassim Hamadeh, CEO and Publisher Michael Simpson, Vice President of Acquisitions Jamie Giganti, Managing Editor Jess Busch, Graphic Design Supervisor John Remington, Acquisitions Editor Brian Fahey, Licensing Associate Mandy Licata, Interior Designer Copyright © 2014 by Cognella, Inc. All rights reserved. No part of this publication may be reprinted, reproduced, transmitted, or utilized in any form or by any electronic, mechanical, or other means, now known or hereafter invented, including photocopying, microfilming, and recording, or in any information retrieval system without the written permission of Cognella, Inc. First published in the United States of America in 2014 by Cognella, Inc. Trademark Notice: Product or corporate names may be trademarks or registered trademarks, and are used only for identification and explanation without intent to infringe. Cover image copyright© 2010 by Depositphotos / дмитрий эрслер. Cover image copyright© 2012 by Depositphotos / Eric Simard. Cover image copyright© 2012 by Depositphotos / Wavebreakmedia. Cover image copyright© 2013 by Depositphotos / Martin Mark Soerensen. Cover image copyright© 2013 by Depositphotos / Bozidar Kalusevic. Cover image copyright© 2012 by Depositphotos / amarosy. Printed in the United States of America ISBN: 978-1-62131-999-3 (pbk) / 978-1-62661-694-3 (br)

This book is dedicated to Dr. Howard Hunt of La Jolla, California: Teacher, Mentor, Inspiration—the good kind of TMI.

Contents Forewordvii

Sidebar Chapter 1: Successful Behavior Change: We are the 33 Percent!

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Opening Statement Chapter 2: Exercise Epidemiology, or What We Know about Exercise, Morbidity, and Mortality13

Witnesses for the Prosecution Chapter 3: Cardiovascular Disease— Cholesterol, the Heart, and the Brain

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Chapter 4: Obesity ← 20x → Type 2 Diabetes

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Chapter 5: Colon, Breast, and Maybe Lung Cancer

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Chapter 6: Osteoporosis

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Witnesses for the Defense Chapter 7: Cardiorespiratory Exercise

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Chapter 8: Resistance Exercise

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Chapter 9: Flexibility Exercise

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Closing argument Chapter 10: Nutrition Basics

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Reducing Recidivism or How I made my parole officer happy Appendix 1: Goal Setting

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Appendix 2: Fitness Testing

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Appendix 3: Biometric Goals and Objectives

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Foreword

I

f you had five minutes to convince someone to make one behavior change that would have the biggest impact on her health, what would you talk about? Many public health advocates would focus on smoking, often referred to as the number one cause of preventable death. I would talk about physical activity. In this book, I present my case for why I think physical activity is the single most important thing you can do to protect and enhance your health. I’ll begin by answering the big question: WHY? Should you exercise just because I suggest it? Because the government recommends it? Because your doctor prescribes it? Well yes, but that’s beside the point because most people won’t buy into a behavior change until they understand WHY. Just as a lawyer lays the foundation for a successful argument during his opening statement, I begin by explaining everything we know about the relationship between health, disease, and physical activity, and everything we know is quite a lot! We’ll start in the 1950s in England, jump to Texas in the 1980s, and end up with a massive pile of data that show conclusively that physically active people between about 40 to 80 years of age, when compared to their inactive peers, are 50 percent less likely to die from any cause (THE MOST IMPORTANT POINT OF THIS BOOK), and are at lower risk for many diseases, including heart disease, stroke, type 2 diabetes, osteoporosis, obesity, and colon and breast cancer. After I make the case for physical activity by presenting you with a veritable mountain of medical facts, I’ll address the next logical question: HOW

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MUCH? The answer to WHY is indisputable, as you’ll see after finishing the first six chapters of this book. The HOW MUCH exercise prescription is an evolving entity, but after a brief review of the history of exercise prescription in the United States, we’ll discuss current, specific guidelines for cardiovascular, muscle strength, and muscle flexibility exercise routines as suggested by the American College of Sports Medicine (ACSM). Finally, with WHY and HOW MUCH behind us, we’ll review MOTIVATION. I know once you finish this book you will be motivated to exercise. However, most people who begin a new exercise program fail to maintain it. I’ll do my best to give you the tools you need to be one of the success stories. Then, like a parent launching his child off into the world, I’ll let you go. But you’ll always have this book to open again when you need reassurance and a reminder about why you should be a physically active person. Dog-ear this page now! Put it on your fridge! Paste it on your Facebook page! Going from being sedentary to participating regularly in a modest cardiovascular exercise program (i.e., walking) reduces your risk of dying prematurely by 50 percent!

i. sidEbar

A sidebar is a private conversation lawyers have with the judge during a trial. Before I present my main case that explains WHY exercise is essential, I want to start by addressing the elephant in the room: Most people don’t exercise. As the judge and jury in this case, you—the reader—should wonder why this is so. The reasons are varied and have made it very difficult for public health officials to get more Americans moving. This first section is a discussion about behavior change, a chat between the two of us. It may give you some ideas that increase the likelihood of your success when starting a new exercise program.

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Successful Behavior Change: We Are the 33 Percent!

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hen was the last time you successfully and permanently changed a longterm, deeply ingrained habit? Chances are the answer to that question is, never. And the reason I can say that with confidence is because research tells us that when a group of people attempt to change, 50 percent drop out after a few months and perhaps as few as 33 percent of those people are ultimately successful.1 The rest of this chapter will review two theoretical constructs created by scientists to explain behavior (and thus suggest mechanisms for change), and give you some practical tools to facilitate change. These tools will be fully developed in the Appendices located at the end of this book.

Stages of Change (The Transtheoretical Model) My favorite behavior change theory was created by Dr. James Prochaska at the University of Rhode Island in the 1970s, when he was working with people who were trying to quit smoking. It has since taken on a life of its own and is popular with public health professionals, who use it to provide guidelines for creating behavior change programs. Boiled down to its essence, Stages of Change categorizes people into one of five stages, according to their awareness of and readiness to change a behavior. The practical application of this theory is that it directs us to consider different plans of action when we’re dealing with

1  DISHMAN, R.K. (1991). Increasing and maintaining exercise and physical activity. Behavior Therapy, 22, 345–378.

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people in different stages of change. Using exercise as our habit for discussion purposes, let’s briefly examine each stage of change.

Pre-contemplation: “I’m Not Thinking about This.” Someone in the pre-contemplation stage regarding exercise never thinks about exercise unless someone else brings it up first. The easiest way to remember this stage is to link the prefix “pre-” (= before) with the root word “contemplation” (= thinking about). By definition, a person not thinking about exercise must be sedentary, and this absence of physical activity, as we will learn shortly, puts them at risk for developing a number of illnesses. In order to help this person change his behavior, we have to provide education. Depending on the pre-contemplator’s exact mindset, that education could include information that explains: • Healthy benefits of exercise • Unhealthy side-effects of being sedentary • How to overcome perceived barriers to exercise like time, lack of skill, poor environment

Contemplation: “I’m Thinking about This but It Could Be Six Months before I Start.” Someone in the Contemplation stage has begun to consider changing her behavior, but it will be a month or more before she will actually begin an exercise program. In other words, change is a small desire with no concrete plan in place that would make it very likely to occur. In order to increase the likelihood that this person will start to exercise, she needs further education about the benefits of physical activity and the skills necessary to construct an action plan, including how to: • Create SMART goals2 • Locate allies and resources • Set an exercise schedule

Preparation: “I Will Begin Exercising This Month.” In Preparation, a person is taking concrete steps to facilitate behavior change, and the initiation of change is imminent. These steps could include:

2  See Appendix 1.

Successful Behavior Change: We Are the 33 Percent  |  5

• Contacting a local fitness club to ask about membership dues or signing a club contract • Buying new sneakers • Verifying that the high school has a public quarter-mile track • Coordinating exercise time with a friend • Reviewing exercise goals

Action: “Today, I Begin.” Day 1 of the exercise program marks the beginning of the Action stage. This stage is often considered the most volatile stage in behavior change because it is difficult to know if the person will show up for Day 2 or Day 13 of his exercise plan. In order to stack the odds in his favor for continued success, it is important to focus on strategies that support the behavior. These include: • Praise and positive reinforcement3 • Fitness assessment4 • Exercise diaries • Goal assessment

Maintenance: “Wow, I’ve Been Doing This for Six Months!” Six months after starting and maintaining a new behavior is considered the point at which most people have permanently adopted a new behavior. Someone in Maintenance has become a person who will probably exercise regularly for the rest of her life, barring any drastic, major life change.

Relapse: Prepare or Become One of the 66 Percent In all stages except pre-contemplation and maintenance, the chance that someone moves to another stage is high. When he moves “backward” to a prior stage of readiness to change, we call this relapse. The most important concept to remember regarding relapse is that MOST PEOPLE SUCCUMB! If you fail to successfully change your behavior, you are NORMAL. Failure to change is the most common outcome of behavior change programs. Generally we expect about two thirds, or 66 percent of people to be unable to maintain a behavior change. If you want to be one of the 33 percent, then you need to have a plan of action in place so that when you suffer a minor setback (which 3  See Appendix 1. 4  See Appendix 2.

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happens to everyone, even people who successfully alter their behavior), it does not become a major failure. People who are prepared for relapse have considered this possibility from multiple wellness perspectives, and they: • Expect minor setbacks (are psychologically prepared) • Have a support person/network in place (socially prepared) • Have SMART short-term goals5 (intellectually prepared) • Create flexibility in their work and home environments (occupationally prepared) • Recognize that in the scheme of things, minor setbacks are exactly that: MINOR (spiritually prepared) • Know how to treat exercise-induced discomfort and injury (physically prepared)

Stages of Change Summary The transtheoretical model says that people are in one of five stages of change. We need to craft our motivational messages in at least five different ways to be able to communicate effectively with people in different stages. Most people suffer setbacks when they try to change behavior, and one important skill needed to successfully change is to be prepared ahead of time to deal with small mistakes.

Social Cognitive Theory Another favored concept in behavior change planning comes from the Social Cognitive model created by Dr. Alfred Bandura at Stanford University. According to this model, I can predict people’s behavior if I know two things about them: Outcome Expectation and Self-Efficacy. Furthermore, I can increase the likelihood they will engage in a behavior if I improve those two variables. Because these two variables are behavior specific, I’ll use exercise behavior to explain them.

Outcome Expectations Simply put, an Outcome Expectation is someone’s belief that when she engages in exercise, a certain outcome will occur. That outcome could be perceived as positive (burned calories) or negative (hot and sweaty). Someone with positive Outcome Expectation is someone who is likely to exercise. Someone with

5  See Appendix 1.

Successful Behavior Change: We Are the 33 Percent  |  7

negative Outcome Expectation will not exercise. In order to make someone’s Outcome Expectation positive, I need to: • Educate them about the positive aspects of exercise • Reorient their thinking about the negative aspects of exercise –– Hot and sweaty = physical proof you are burning calories

Self-Efficacy Self-Efficacy is the perception a person has about his own competency to engage in a behavior. Someone who feels incompetent (“I don’t know how to use weight room equipment.”) is unlikely to engage in exercise, while feelings of competency increase exercise participation. Someone with high exercise selfefficacy has confidence and competence and therefore is likely to perform it. Bandura’s theory states that there are four ways to increase someone’s exercise self-efficacy.

Performance Mastery Performance mastery is the single most effective way to increase someone’s self-efficacy. To quote a famous advertising slogan, it can be summarized as “Just Do It.” Start walking. Use the weight equipment at your gym. Go to a yoga class. The more frequently you do these things and have success (“I WAS able to bench press the 45-pound bar with a little help from a friend who spotted me.”), the greater your self-efficacy becomes. And as your self-efficacy improves, your willingness to raise the bar improves. Of course, it is important to have realistic expectations about your ability to “Just Do It” because the key to Performance Mastery is a successful bout of exercise. Therefore, when planning your exercise routine, you should build steady progression into your workout. Start with something you have every reason to expect you can accomplish (“My goal today is to walk two laps around the quarter-mile track”) and then increase your output over time. (“Two weeks from now my goal will be to walk four laps.”)

Vicarious Experience When we turn to role models and emulate their behavior, we are using vicarious experience to motivate us. If we choose good role models—that is, role models who are appropriate for us, who resemble us across as many variables as possible (age, sex, socioeconomic background, etc.)—their performance of the exercise we hope to adopt can help us become more confident. “Well, if Rick can do

8  |  Why Exercise is Important

that beginner’s yoga class, I definitely can. We grew up together, go to the same school now—he isn’t different from me.” When you’re thinking about adopting a new exercise behavior but still feel shaky about the whole thing, find somewhere that people like you go to do it and WATCH them. If you don’t know where people like you go to exercise, ask your friends (who tend to be like you). If that doesn’t work, ask a trusted mentor/teacher/adviser. Someone will have the information you need.

Social Persuasion In one word: Encouragement. Find people around you who will encourage you to exercise and compliment you when you are successful. Use your social media outlets (Facebook, etc.) to document your exercise goals and progress for your friends, and explicitly tell them to “like” your achievement posts and to post their own words of encouragement on your page, particularly when you mention you have accomplished something significant. Consider hiring a personal trainer or wellness coach, particularly during your early weeks in the Action stage. Adopt technology that can act as a proxy for a personal trainer, giving you positive feedback when you achieve your exercise goals. Personal tech could include data-recording wristbands like Flex, FuelBand, or UP and mobile apps like MyFitnessPal and RunKeeper. Web tech could include a site like MyPlate. gov, where you can track your exercise in an electronic diary.

Physiological Awareness During exercise, your body’s function changes drastically (the reason it is so beneficial), but those changes may be interpreted as either good or bad. For example, when your heart begins beating more rapidly when you are riding your bike in a spinning class, you could wonder if that is normal, and if unsure, start to worry that something bad is happening to you. If this physical stress leads to psychological stress, your self-efficacy will decrease. It is important to understand clearly what will happen to your body when you exercise (explained later in this book), so you know when it is appropriate to worry that something is wrong, or when to accept that, “Hey, this is just what exercise feels like.”

Social Cognitive Theory Summary Performance Mastery is the best way to increase your self-efficacy. Start exercising. Turn to your friends if you are unsure what you can accomplish—if they can do it, you can too, eventually. Ask your friends to actively support your

Successful Behavior Change: We Are the 33 Percent  |  9

behavior change by giving compliments and kudos when you earn them. Use technology supports. Educate yourself about the typical physiological changes that accompany exercise. Exercise does change you, but that’s the whole point.

ii. OpEning statEmEnt

At trial, an opening statement is the opportunity to present an overview of the case you intend to make to the jury. This next chapter covers decades of research that have proven conclusively that physically active people have better health outcomes than sedentary individuals.

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Exercise Epidemiology, or What We Know about Exercise, Morbidity, and Mortality

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xercise has been recognized as behavior that enhances human health since at least the time of the Greco-Roman empires. Both Hippocrates and Galen wrote about the essential nature of physical activity in connection with good health.1 I In the 1950s, Dr. Jeremy N. Morris in the United Kingdom began a systematic examination of the relationship between physical activity, coronary artery disease, and death by studying London bus drivers/conductors and postal deliverymen/post office workers.2 Morris’s data showed that physically active conductors who walked the double-decker buses punching tickets and climbing on average 500–750 steps/day were about 67 percent less likely to develop coronary artery disease compared to the sedentary drivers (90 percent of the job time sitting). Similar effects were seen in postal delivery men who cycled or walked their delivery routes as opposed to postal workers who staffed the mail stations. Morris concluded that, “men doing physically active work have a lower mortality from coronary heart disease in middle age than men in less active work.”3 At the same time, Dr. Ralph Paffenbarger began collecting data on San Francisco longshoremen, people who worked loading and unloading the cargo ships. After 16 years observing and collecting data, Paffenbarger’s group 1 http://www.thelancet.com/journals/lancet/article/PIIS0140-6736%2812%2961205-7/ fulltext 2  J. N. Morris, J. A. Heady, P. A. B. Raffle, et al. Coronary heart disease and physical activity of work. Lancet, 1953; 265(6795): 1053–57. 3  J. N. Morris, J. A. Heady, P. A. B. Raffle, et al. Coronary heart disease and physical activity of work. Lancet, 1953; 265(6796): 1111–20.

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published a study in 1970 that Want to view Pafenbarger’s showed the most active longshoreresults? Visit: http://www. men (who burned 1000 calories/ nejm.org/doi/full/10.1056/ day more than the rest of the group) NEJM197005142822001 were about 44 percent less likely to die from coronary artery disease when compared to their less active coworkers.4 During that same decade, Dr. Steven Blair began tracking corporate executives who attended the Cooper Aerobic Center in Dallas. This work marked one of the first attempts to quantify the study participants’ physical fitness levels using actual physiological data rather than a questionnaire self- or observational-report. The men and women in this study were placed on a treadmill and performed a maximal effort test (the treadmill was accelerated and grade increased throughout the Want to view Blair’s results? Visit: test), considered the most effective http://jama.jamanetwork.com/ way to evaluate someone’s physical article.aspx?articleid=379243 fitness level. His group then tracked the people for about eight years, recording how many people died during that time. The results of this study were published in 1989, and the death rate data were compared across five levels of physical fitness (known as fitness quintiles). Blair’s results indicated that death rates in people in the second worst fitness quintile (low-active people) were approximately 50 percent lower than rates for people in the worst fitness quintile (sedentary people). This was true for Want to view the Myers study? both men and women, though men Visit: http://www.nejm.org/doi/ showed a substantially higher overall full/10.1056/NEJMoa011858 death rate, which is a typical sex difference caused by higher rates of cardiovascular disease in 40-to-50-year-old men versus women.5 In 2002, Dr. Jonathan Myers and colleagues published a study replicating the techniques used in Dr. Blair’s work, but looking only at men who had been 4 R. S. Paffenbarger, M. E. Laughlin, A. S. Gima, et al. Work activity of longshoremen as related to death from coronary heart disease and stroke. N Engl J Med, 1970; 282:1109–14. 5 S. N. Blair, H. W. Kohl 3rd, R. S. Paffenbarger Jr., D. G. Clark, K. H. Cooper, and L. W. Gibbons. Physical fitness and all-cause mortality. A prospective study of healthy men and women. JAMA, 1989, Nov 3; 262(17): 2395–401.

ExErcisE EpidEmiology | 15

referred to their hospital for exercise stress testing. Their data compared the death rates of men who, after testing, were declared disease free against men in whom the stress test indicated the presence of cardiovascular disease. In their 11 years of follow-up, Myers and his colleagues saw data very similar Want to view Hu’s results? Visit: http:// to Blair’s: low-active, healthy men www.nejm.org/doi/full/10.1056/ had about a 50 percent reduction NEJMoa042135 in risk of dying compared to the healthy sedentary men. The protective effect of exercise was also seen in low-active men who had been diagnosed with heart disease, though the risk reduction was only about 25 percent for those individuals.6 In 2005, Dr. Frank Hu and colleagues presented data from a large cohort of female nurses from the New England area who had been tracked for 24 years and commented upon the association between obesity, exercise, and mortality. This study design relied on self-report of exercise rather than actual physiological measurement of fitness, but the data presented a familiar picture: when they compared women of normal weight (controlled for the effects of obesity), those who exercised for 1–3.5 hours a week were about 35 percent less likely to die. Women who exercised more than 3.5 hours a week were about 50 percent less likely to die when compared to normal-weight women who exercised for less than one hour a week.7

Exercise Epidemiology Summary Over the past 50 years, we have accumulated enough evidence to establish as scientific fact that physical activity and exercise protect and promote good health. If you are sedentary and you begin a modest exercise program, you will cut your risk of dying prematurely by 50 percent. This applies if you are a man or a woman. It’s never too late to make this change—people as old as 80 have an increase in longevity if they exercise.8 In 2012, researchers tried to quantify the number of life years gained from exercise, and a generally healthy individual 6 J. Myers, M. Prakash, V. Froelicher, D. Do, S. Partington, and J. E. Atwood. Exercise capacity and mortality among men referred for exercise testing. Exercise capacity and mortality among men referred for exercise testing. N Engl J Med., 2002; Mar 14, 346(11): 793–801. 7 F. B. Hu, W. C. Willett, T. Li, M. J. Stampfer, G. A. Colditz, and J. E. Manson. Adiposity as compared with physical activity in predicting mortality among women. N Engl J Med., 2004; 351: 2694–703. 8 J. Stessman, MD, R. Hammerman-Rozenberg, MD, A. Cohen, MD, E. Ein-Mor, MA, and J. M. Jacobs, MBBS. Physical Activity, function, and longevity among the very old. Arch Intern Med., 2009; 169(16): 1476–83.

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(i.e., no chronic illness or a really bad habit like smoking) can expect to gain between four to five years of life on average.9 Exercise advocates would argue that not only will you have those years, but on average, they and all your other years will be of much higher quality. Putting life into your years is one of the benefits of exercise. Chapters 3 to 6 will explain how this happens.

9  Leisure Time Physical Activity of Moderate to Vigorous Intensity and Mortality: A Large Pooled Cohort Analysis. From-http://www.plosmedicine.org/article/ info%3Adoi%2F10.1371%2Fjournal.pmed.1001335

iii. WitnEssEs fOr thE prOsEcutiOn The next three chapters will describe in detail how exercise helps reduce your risk of contracting common diseases, including obesity, diabetes, osteoporosis, and various forms of cardiovascular disease. Once you’ve read through this information, you will have a firm understanding of why sedentary behavior is so dangerous for your health.

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3

Cardiovascular Disease— Cholesterol, the Heart, and the Brain

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he evidence in Chapter 2 allows me to tell you with conviction that exercise will reduce your risk of dying prematurely. Over the next few chapters, we will elaborate on this topic, starting with the most important way exercise helps us—by reducing our risk of developing cardiovascular disease. Cardiovascular disease, or CVD, is the perennial leading cause of death in the United States because it kills the largest percentage of people over 65, the age group with the highest mortality rate (see Figure 1). It is also the second leading cause of death for those between 25–64 years of age.

The Cardiovascular System The cardiovascular system is comprised of the components of the body that move and transport blood and includes the heart, arteries, and veins. Your heart is the pump that provides the force which propels blood throughout the body. The arteries carry fully oxygenated blood away from your heart when it contracts, and the veins return blood back to your heart after oxygen has been extracted. Any problem with these three elements constitutes a form of CVD. Normal blood flow in the body is important because blood supply has many transportation responsibilities. These include: • Carrying oxygen and other nutrients like sugar and fat to our cells. Without these things, we could not produce sufficient energy to survive. • Removing waste products created through normal metabolic processes or when cells are damaged.

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Aged 1–24 years Number of deaths = 39,086

25 3

38

7 12

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Aged 25–44 years Number of deaths = 112,117

Unintentional injuries (38%) Homicide (13%) Suicide (12%) Cancer (7%) Heart Disease (3%) All other causes (25%)

25 32 6

Aged 45–24 years Number of deaths = 493,376

32

44 4

32

7

21

Cancer (32%) Heart Disease (21%) Unintentional injuries (7%) Chronic lower respiratory diseases (4%) Chronic liver disease and cirrhosis (4%) All other causes (32%)

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12

Unintentional injuries (25%) Cancer (14%) Heart Disease (12%) Suicide (11%) Homicide (6%) All other causes (32%)

Aged 65 and over Number of deaths = 1,796,620

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5

22 6 7

Heart Disease (27%) Cancer (22%) Chronic lower respiratory diseases (7%) Stroke (6%) Alzheimer’s disease (5%) All other causes (34%)

Figure 3.1. Percent distribution of five leading causes of death, by age group: United States, preliminary 2010. NOTE: 2010 data are the most recent official CDC data currently available. Source: CDC/NCHS, National Vital Statistics System. Copyright in the Public Domain.

• Ferrying immune system cells to invasion sites to combat viruses and bacteria. • Delivering hormones and enzymes to areas where we want chemical reactions to happen or happen more quickly, for example, when we start to exercise. CVD is an umbrella term that includes a spectrum of diseases, including coronary heart disease (also known as coronary artery disease or ischemic heart disease), which causes heart attacks; stroke (ischemic and hemorrhagic varieties), which causes brain attacks, high blood pressure (hypertension); and rheumatic heart disease. To illustrate the beneficial effects of exercise, we will talk primarily about coronary artery disease (CAD), the underlying cause of which influences all other forms of CVD except rheumatic heart disease, which is initiated by a bacterial infection.

“Bad” Cholesterol The key to understanding coronary artery disease is knowing about a substance you’ve heard about in countless ads on TV: cholesterol. Cholesterol is a form of fat produced by your body (and consumed in foods) that your body uses to construct healthy cell walls, aid food digestion, and assist in vitamin (vitamin D) and hormone (estrogen, testosterone) production. It is an essential component

Cardiovascular Disease—Cholesterol, the Heart, and the Brain  |  21

of the human body. However, it has one very unfortunate and unintended sideeffect that leads to CAD. Before we explain that side-effect, you need to know that in order for your body to transport cholesterol in your blood, it has to break it up into smaller packages. The two packages most important for this discussion are known as HDL (high-density lipoprotein) and LDL (low-density lipoprotein), or “good” and “bad” cholesterol, respectively. The reason LDL is referred to as the bad molecule is because it initiates a process called atherosclerosis, the build-up of plaque inside an artery wall. The exact mechanism by which LDL does this is not clearly established, but one theory is that with normal use, the inner walls of your arteries sustain slight damage, causing microscopic perforations that allow small LDL molecules to penetrate the artery wall. Once inside your artery, the immune system mounts a response to contain what is a foreign invader (LDL is not supposed to be inside an artery, after all). The immune system chemically alters the LDL molecule, changing it into a foam cell, which acts just like it sounds—forming a foamy barrier around the LDL molecule. This “glues” it in place in the artery wall, preventing the LDL from moving. As this process happens over and over again, the inside of your artery wall begins to fill up with plaque, which causes the inner wall of the artery to bulge out into the open space (the lumen) where blood normally flows. Over decades of life, as this process recurs, plaque build-up increases, and the lumen (open space) gets smaller and smaller, leaving less and less room for blood to flow (in medical terms, your artery becomes occluded). Eventually, the space is so small and your blood flow so compromised, that you begin to suffer side-effects. In coronary artery disease, this process happens in the arteries supplying your heart, so in its advanced stages, CAD results in low blood flow to the heart. The bulging plaque may also rupture, causing a massive blood clot to occur blocking all blood flow. If your heart does not get enough blood, it won’t get enough oxygen, so it won’t be able to work properly and the cells may begin to die off. In minor cases, this leads to chest pain (angina) and shortness of breath. In extreme cases, it leads to a heart attack (some cells die). In catastrophic cases, it kills you (so many cells die that your heart is literally broken).

“Good” Cholesterol HDL is known as the “good” cholesterol because studies examining large populations of people have shown a negative correlation between HDL and CVD. That is, when HDL levels rise (above 59 milligrams per decaliter of blood or mg/dl is best), rates of CVD go down. When HDL levels fall (below

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Copyright © 2006 by Grahams Child, (CC BY-SA 3.0) at: http://commons.wikimedia.org/wiki/File:Endo_dysfunction_Athero.PNG.

41 mg/dl), rates of CVD go up. Having an HDL level of 60 or more is considered a protective factor against CVD. HDL’s primary function is to absorb excess cholesterol wherever it finds it and return it to the liver to be reabsorbed. In this way, HDL acts opposite to LDL. LDL delivers cholesterol to cell sites, while HDL takes it away. When we have a lot of HDL in our blood stream, we increase our body’s capacity to absorb excess cholesterol. If HDL encounters LDL cholesterol, it can absorb that, too—even the form of LDL that has turned into foam cells in the artery

cardiovascular disEasE—cholEstErol, thE hEart, and thE Brain | 23

walls IF the encounter happens early enough in the LDL-to-foam-cell transformation process. To summarize, the more HDL you have, the more “sponges” you have in your blood capable of absorbing LDL cholesterol, and the less quickly plaque will build up in your artery walls. Besides preventing and reversing cholesterol deposit in artery walls, HDL may also help prevent CVD by: • Altering the permeability of the blood vessel wall, making it harder for LDL and immune cells to penetrate the walls1 • Changing the action of platelets so that blood clots are less likely to happen (a blood clot is often the immediate cause of a heart attack or stroke)2

How Does Exercise Help? At this point in the discussion, it is important to understand that Most research into the relationship EVERYONE is affected by atherobetween CVD and exercise has evalusclerosis. You, me, your best friend, ated the effect of endurance exercises your uncle are all experiencing what like walking and running, also known is commonly called hardening of the as cardiorespiratory exercise, or arteries (foam cells make your artery cardio for short. walls stiff). This process started in infancy and it will continue until the day you die. You can’t PREVENT atherosclerosis, but you can SLOW IT DOWN. For people who exercise throughout their entire lives, this is THE primary mechanism by which they reduce their risk of CVD.

Increased HDL/LDL Ratio Exercise slows down the progression of atherosclerosis because it can raise HDL molecules and lower LDL molecules in the blood. The exercise effect on HDL is generally stronger than

TIP: It is thought that walking may not be intense enough to significantly alter HDL and LDL levels, so if you want to increase your HDL/LDL ratio, you should exercise as intensely as you can.

1 Michael B. Stemerman, “Lipoprotein Effects on the Vessel Wall ,” Circulation Research. 86: 715–716, 2000. 2 Nofer JR, van Eck M., “HDL scavenger receptor class B type I and platelet function,” Curr Opin Lipidol. 2011 Aug;22(4):277–82. doi: 10.1097/MOL.0b013e32834701de.

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the effect on LDL (sedentary people who start exercising may experience as much as a 20 percent increase in HDL, but only a 10–15 percent decrease in LDL), and exercise intensity seems to be key to maximizing positive change. A 10–20 percent positive change in your cholesterol profile will result in a significant decrease in CVD risk, so don’t let what might seem like small numbers fool you. For someone who is relatively young (under 40), the MOST important way exercise helps prevent CVD is by increasing the HDL/LDL ratio, largely through an increase in HDL. However, exercise has several other positive effects that reduce CVD risk, which becomes more important as we age, the lumen (open space) in our arteries gets smaller, and our arteries get stiffer.

Decreased Blood Pressure Exercise can reduce resting blood pressure. When you exercise, blood flow speed increases. As blood rushes past the surface of the arteries, the faster it moves, the more it stimulates the smooth muscle cells of the arteries to release nitric oxide, a chemical that causes the arteries to relax. Since high blood pressure is a type of CVD, if exercise lowers your resting systolic blood pressure below 140 or your resting diastolic blood pressure below 90, it is directly “curing” you of one form of CVD.

Increased Blood Flow to the Heart Muscle The more intensely you work, the stronger your heart becomes, and the more blood flow it needs. A sedentary person who begins walking will have her body direct more blood to heart cells, as will a walker who starts running. More oxygen to the heart means it can do more work without becoming fatigued.

Increased Blood Clot Breakdown and Decreased Blood Clot Formation You will store more water in your blood, making it more dilute, and blood factors that create and break down blood clots will change in a way that makes it harder for your body to form a blood clot and easier for it to break a blood clot down. This means it is less likely that a clot lodges in an artery, blocking blood flow to your heart or brain.

Cardiovascular Disease Summary CVD starts when LDL penetrates an artery wall and the immune system attacks it. Over decades of life, that process reduces the room in which blood has to

Cardiovascular Disease—Cholesterol, the Heart, and the Brain  |  25

flow, and if atherosclerosis progresses far enough, we develop health problems. Exercise helps reduce risk for CVD by increasing HDL and decreasing LDL, which slows down plaque build-up. When we’re older and our arterial space has gotten smaller, exercise helps by sending more blood to the heart muscle and by reducing blood pressure and blood clotting.

4

Obesity ← 20x → Type 2 Diabetes

A

nother prominent way exercise helps maintain health is by controlling abdominal fat build-up and lowering our chances of developing a form of diabetes commonly referred to as insulin-resistant, or type 2, diabetes. Until about the beginning of the 21st century, type 2 diabetes was also called “adult-onset” diabetes, but within the last 10 to 15 years, as children have gotten fatter and more of them have begun to develop insulin-resistant diabetes, “adult-onset” has become a misnomer. Obesity and type 2 diabetes (T2D) are discussed in tandem because they are intimately related. The title of this chapter alludes to that connection by telling us that someone who is obese is 20 times more likely to develop T2D as opposed to someone who is normal weight. Twenty times! That is an incredible increase in risk. In Chapter 2, we talked about how exercise reduces your risk of dying by 50 percent, or said another way, someone who is sedentary is two times as likely to die versus a peer who exercises. That is impressive, but 20 times as likely is astounding. Put simply, if you stay obese long enough, you will probably become diabetic.

Diabetes To understand diabetes, you have to understand what your body usually does when you eat or drink food containing carbohydrate, what we commonly call sugar. As an example, let’s pretend you decide to eat a packet of sugar at your favorite restaurant. As soon as the sugar enters your mouth, enzymes in your saliva begin to digest it, allowing you to absorb it into your bloodstream quickly. 27

28 | Why ExErcisE is important

Copyright © 2006 by Meiquer, (CC BY-SA 3.0) at: http://commons.wikimedia.org/wiki/File:Insulin_glucose_metabolism.jpg.

Your brain is very particular about the amount of sugar you have in your blood, so when this large rush of sugar floods in, the brain immediately says, “GET THAT OUT OF HERE NOW!” Why? Because, assuming you’re healthy, your blood already has all the sugar in it your brain expects (and wants) and anything beyond that is too much. As I said, your brain is VERY particular about this. In a person who does not have diabetes, the response to this demand to lower blood sugar is a surge in the production of a hormone called insulin. Insulin is produced in specialized cells in the pancreas, so as the brain signals for sugar to be absorbed, the pancreas immediately ramps up insulin production. Insulin surges into the blood stream and at the same time cells begin to shout for insulin to come to them, saying, “Bind to this receptor on my cell wall, insulin, and I will take some of that sugar out of the blood!” (See Figure 3.) If insulin hears the signal from the cell wall receptor, it links to the cell and causes a cascade of events that allows the cell wall to open and glucose to enter the cell. Within a On a blood test, blood sugar is called matter of minutes, a healthy person glucose. producing normal levels of insulin will return her blood sugar back to the level her brain expects, and all is well. Unfortunately, for some people, the system malfunctions and they have difficulty absorbing blood sugar. If the

Obesity ← 20x → Type 2 Diabetes  |  29

malfunction is severe enough, and they are unable to get their blood sugar below 126 milligrams per decaliter of blood, they are diagnosed with diabetes. The fact that there is a type 2 diabetes suggests a type 1 form of the disease. Type 1 diabetes, or “insulin dependent” diabetes, occurs when the cells in the pancreas produce very little or no insulin. This disease often manifests itself in childhood, so type 1 used to be referred to as “child-onset,” but because children are developing type 2 diabetes more frequently now, it no longer makes sense to use that label. Instead, we say type 1 diabetics are “insulin dependent”—that is, their bodies can’t make insulin, so they are dependent on a laboratory to provide it. Out of all the diabetic cases diagnosed each year in the United States, only about 10 percent of them are type 1 diabetes. Type 2 diabetes has a very different etiology. During the initial phase of this disease, people are able to produce normal amounts of insulin from their pancreatic cells. However, even though they can make insulin, their bodies are unable to use it properly. Why? Well, let’s review the string of events that occur when you eat sugar and it gets in your blood: 1. 2. 3. 4. 5.

Brain yells, “Sugar alert!” Pancreas cranks out insulin. Cells yell, “Come here, insulin!” Insulin binds to a cell receptor. Cell wall opens to let in sugar.

For a type 2 diabetic, steps 1, 2, and 5 work correctly, but steps 3 and 4 do not because the cells of the body are beginning to become (or have become) insulin resistant. They don’t attract and bind insulin as easily as they used to. This happens because two things have changed. • Cell receptor sensitivity is decreased Instead of yelling, “Come here, insulin!” the cells only say it. “Come here, insulin.” Period, no exclamation point. Or they mumble it, “Com … re … lin.” From a biological perspective, we calls this loss of volume a reduction in the cell receptor signal strength, or decreased receptor sensitivity. Normally, cell receptors send a robust chemical signal out into the bloodstream to attract the hormones or enzymes they want to bind with. With type 2 diabetes, that signal is muted.

30  |  Why Exercise is Important

• Cell receptor number is decreased I n addition to having to hear a weaker signal, insulin is presented with a second challenge—the number of cell receptors that are normally available for insulin to bind to have decreased. Some of the receptors that used to be working have been turned off. Therefore, there may be plenty of insulin around, but if it has no place to attach on the cell wall, it can’t help open the door to let sugar in.

How Does Exercise Help? The answer to this question becomes very apparent once we understand how the insulin-sugar-cell receptor–group acts in response to a bout of exercise. First, a question for you: Do your cells need more or less sugar during exercise? To answer that, you need to know that sugar is used by your cells to produce energy, or ATP. In fact, once you start moving your body around vigorously, the amount of ATP your body produces to support that movement can increase 20 times above your resting energy requirements. At higher levels of exercise intensity, sugar is the primary fuel source for that ATP production. So what happens when you begin to exercise? Let’s use our five-step model again to illustrate: 1. Brain yells, “Sugar alert!” only this time what it means is, “This body is moving! Start releasing sugar stored in the liver into the blood because we need it to produce ATP.” 2. Pancreas cranks out insulin. 3. Cells yell, “Come here, insulin!” 4. Insulin binds to a cell receptor. 5. Cell wall opens to let in sugar. Your body’s response to exercise is the same response it has to eating sugar, except that instead of lasting only a few minutes, this series of events continues for as long as you are working out. Exercise engages your insulin-sugar-cell receptor–system and makes it work very hard! And what happens to a body system that you use vigorously on a regular basis? IT GETS BETTER. If it is already at its peak, it stays at its peak. Lift weights, and your muscles get stronger and stay strong. Stretch regularly, your muscles get longer and stay long. Move your body regularly, and your insulinsugar-cell receptor–system gets and stays primed for action. Insulin receptor

Obesity ← 20x → Type 2 Diabetes  |  31

signal strength stays strong (receptor sensitivity stays high), and the number of active insulin receptors on cell walls stays high in a body that undergoes regular exercise.

Diabetes Summary Insulin is needed for cells to absorb sugar from the blood. When the body doesn’t produce enough insulin (type 1 diabetes) or that insulin can’t work effectively (type 2 diabetes), sugar absorption falters and your blood sugar rises. This is dangerous because too much sugar in your blood causes damage to other body tissues, particularly tissues of the nervous system. Exercise helps prevent the development of type 2 diabetes because it makes you use the insulin-sugarcell receptor–group on a regular basis and at a high level. Unfortunately, the reverse is true. If you are sedentary, you don’t ask your body to convert sugar into ATP very often or at high levels periodically. Insulin receptors get turned off and the ones left on don’t work as efficiently as they used to. As a result, sedentary people are at increased risk for developing type 2 diabetes. Ninety percent of all new diabetes cases diagnosed in the United States are type 2.

Obesity Since obese people are normally fairly sedentary people too, it’s not surprising that obesity and type 2 diabetes have such a strong positive correlation (remember, an obese person is 20 times as likely to become diabetic versus someone of normal weight). Sedentary people don’t use their insulin-sugar-cell receptor–system very much; that system atrophies, and they become diabetic. There is also a connection between being sedentary and gaining weight. When we move, sugar or fat is used to produce ATP so our muscles can function. When we don’t move, some of the fat and sugar we eat gets stored as fat in our bodies, assuming we consume more calories than we burn through normal metabolism and exercise. Sedentary people tend to gain weight, particularly in our society where access to food is so open. Before we talk further about obesity, let’s review the standard definition of obesity so we understand what it means to call someone obese. From a medical perspective, obesity is determined by comparing a person’s height and weight using a metric called Body Mass Index, or BMI. Depending on your score, you are classified into one of four categories: underweight, normal weight, overweight, obese. Within the obese category, there are three subclassifications:, Class 1, Class 2, and Class 3.

32 | Why ExErcisE is important

Table 4.1. Classification of Overweight and Obesity by BMI, Waist Circumference, and Associated Disease Risks disease risk* relaTiVe TO nOrMal WeigHT and WaisT CirCuMFerenCe BMi (kg/ M2) Underweight

OBesiTY Class

Men 102 CM (40 in) Or less WOMen 88 CM (35 in) Or less

Men > 102 CM (40 in) WOMen > 88 CM (35 in)

< 18.5

–

–

Normal

18.5–24.9

–

–

Overweight

25.0–29.9

Increased

High

Obesity

30.0–34.9

I

High

Very High

35.0–39.9

II

Very High

Very High

40.0+

III

Extremely High

Extremely High

Extreme Obesity

Source: NIH. Copyright in the Public Domain.

Normal weight is thought to be the category that carries the least amount of health risk—so underweight, overweight, and obese people are theoretically more likely to develop health problems. This thinking is controversial, as some data demonstrate people who are overweight are actually less likely to die compared to normal weight peers.1 I believe BMI is a poor way to measure someone’s health risk, particularly a young person, because people with extra muscle weight often get classified as overweight even though they may be healthier than normal-weight people with less muscle. My preference for identifying how fat storage may impact health is to talk about waist circumference. Waist circumference is a more meaningful measure of health risk because of two factors. 1. Strength training of the musculature around the waist (abdominals and obliques) does not result in significant enlargement of those muscles (i.e., if you do a lot of sit-ups, your waist does not get bigger).

To measure your waist, find the narrowest point between your belly button and your breastbone. Wrap the tape around that narrowest point, making sure to keep the tape level all around your body.

1 JAMA. 2005 Apr 20;293(15):1861–7. Excess deaths associated with underweight, overweight, and obesity. Flegal KM, Graubard BI, Williamson DF, Gail MH.

Obesity ← 20x → Type 2 Diabetes  |  33

2. Researchers have established that having a lot of fat around your middle, and close to your other internal organs, is a very risky place to store it. It’s also a practical and convenient way to talk about health risk because men already know the number (their pants size is related to their waist size) and it takes little skill and inexpensive equipment (a tape measure) to assess it. When a woman’s waist is 35 inches or larger and a man’s is 40 inches or more, they are at increased risk for type 2 diabetes, high blood pressure, and CVD.

How Does Exercise Help? When you move, you burn calories. It’s a pretty simple relationship. Move more = burn more. If you move more and control your caloric intake (eat less), you lose weight.2 Sounds simple, right? Then why is it so difficult for many, many people to lose weight—and even more difficult to keep the weight off? The answer to the first part of that question is this number: 3,500. This is the number of calories in a pound of fat, about equal to the number of miles between New York City and London. Is it convenient to get from New York to London? Not really—it takes seven to eight hours in the air, not counting the time spent getting to the airport, dealing with TSA, and taking the Tube into London. Is it easy to burn up 3,500 calories? Not really—in about 45 minutes of vigorous exercise, the amount of time many people would typically spend working out, you can expend about 500 calories. At that rate, it takes 5 hours 15 minutes to burn one pound of fat. Not quite as long as it takes to fly to London, but pretty long! Another way of thinking about this is you have to exercise EVERY DAY OF THE WEEK for 45 minutes to lose one pound of fat. Whoa—no wonder it’s tough.

Weight Loss IS Complex The answer to the second part of the question, why is it hard to keep weight off, is because in order to make this kind of permanent change in your body, you have to alter many habits, not just how much you exercise. Faculty at Brown University and the University of Colorado have been managing a database, the National Weight Loss Registry, of habits associated with people who have lost at least 30 pounds of weight and have been able to maintain that weight loss for at least one year. When the researchers combed

2  This is a very simplistic view of weight loss, which may be affected by your genes and your sex.

34  |  Why Exercise is Important

through their data to look for interesting trends, they identified seven habits adopted by successful people:3 • 200 minutes/week moderate-intensity exercise • Less than 10 hours/week watching TV • 1,380 calories/day, less than 30 percent from fat • Eat same foods regularly; do not splurge on high-calorie foods weekends/ special occasions • Eat breakfast daily • Do not eat in response to emotional distress or external food cues (like a buffet) • Weigh in at least weekly; record food intake daily

Obesity Summary Thirty-six percent of American adults are obese. This number has been rising steadily since the advent of the personal computer, around 1980. Our lifestyles have become more sedentary at work, home, and play. We eat more. If you want to lose weight, you should exercise, but because there are 3,500 calories in a pound of fat, you have to do more than exercise. Examine your diet, and eat less. Change your environment to support more active habits. Learn how to deal constructively with stress. Begin keeping exercise and diet diaries to help you stay on track.4

3 http://www.nwcr.ws/ 4  See Appendix 1.

5

Colon, Breast, and Maybe Lung Cancer

T

he relationship between exercise and cancer is an interesting and evolving one. For many years, we have known that exercise reduces someone’s risk for colon cancer. More recently, we have established that exercise reduces breast cancer risk in women, and accumulating research is beginning to suggest that exercise may also reduce lung cancer risk.

What Is Cancer? Cancer is a disease where the cellular machinery responsible for replication (making new cells) goes awry, and cells begin to produce too many irregular copies of themselves. As these irregular copies multiply, they form masses called tumors. If aggressive tumors (malignant tumors) are left uncontrolled, their presence in sensitive parts of the body can kill us because they divert large amounts of blood from other, healthy cells around the tumor. When the healthy cells can’t get enough oxygen, they begin to die, and if enough cells die in, say, your liver, that organ stops working, and you die. What causes cancer is the $64 trillion question. The truthful answer is, “We don’t know.” There are many potential influences, and different forms of cancer are likely caused by very different things. Genes obviously play a role, and many geneticists are busy trying to identify genetic information associated with increased cancer risk (the BRCA genes associated with breast cancer in females are a good example). Whatever the cause, cancer begins when there is damage to the cellular material responsible for cell replication, called DNA and RNA. DNA is your

35

36  |  Why Exercise is Important

genetic blueprint, the house plans that carry all the information needed to build your body. RNA are the cellular architects that take the information from the DNA and tell the various craftsmen in your body to build whatever needs building. Need a new cell wall to contain a new cell? Messenger RNA gets that information from your DNA and presents it to the rest of the cell so it can begin construction. If the information in your DNA is somehow damaged—say you spill coffee on your blueprints and you can no longer read if the wall is supposed to be 10 feet long with wooden support beams or 12 feet long with a center steel support beam—bad things can happen. The wall gets made incorrectly, or in the case of cancerous cells, the cell is made in such a way that it has an accelerated reproduction cycle and the ability to build lots and lots of blood vessels that support a rapid growth cycle. If it grows very quickly and has the potential to spread to different parts of your body, it is considered a malignant tumor.

Colon Cancer The colon is the part of the body that connects your stomach to your anus, also known as the large intestine After acids in the stomach break down the food you eat, it travels through the small and large intestines, where nutrients are absorbed into your blood. Your colon is the last chance for your body to absorb water and other nutrients from solid waste before it is excreted, and it is composed of many folds, or pouches, of tissue that increase the amount of surface area that can come into contact with solid waste (and thus have a chance to absorb necessary nutrients) before defecation. Unregulated cell growth in this area (or the rectum) is defined as colorectal cancer, which we usually call colon cancer.

How Does Exercise Help? About ten percent of all colon cancer cases are linked to inactivity.1 There are two ways exercise is thought to decrease colon cancer risk. The first is primarily a mechanical one. When you exercise and move your body, your viscera (internal organs) move as well. This movement stimulates a process called peristalsis, the rhythmic contraction of muscular rings around your colon that propels solid waste through the colon to the rectum and anus. In other words, people who exercise regularly go to the bathroom and excrete solid waste regularly. The 1  I-M. Lee, E. J. Shiroma, F. Lobelo, P. Puska, S. N. Blair, and P. T. Katzmarzyk. Effect of physical inactivity on major non-communicable diseases worldwide: An analysis of burden of disease and life expectancy. Lancet, 2012; 380 (9838): 219–29.

colon, BrEast, and mayBE lung cancEr | 37

Copyright in the Public Domain.

more quickly you excrete solid waste from your body, the less time it has to linger next to the vulnerable cell walls of your colon, and therefore the less time it has to cause damage to the cellular lining. Damage to that cellular lining is something that may increase cancer risk. The other effect exercise has is that it alters the activity of transforming growth factor (TGF). TGF, also called tumor growth factor, is a chemical that speeds up cell growth. People who exercise regularly have less TGF in their blood, indicating that if that person were to develop a tumor, it would be relatively slow growing compared to a sedentary individual. The more slowly a tumor grows, the more likely the body’s natural defenses are able to intercede and kill those cells off, thus essentially catching cancer early and destroying it before it can grow large enough to become a concern. Slow growth also allows for early detection, which is often the difference between a cancer survivor and a cancer victim.

38  |  Why Exercise is Important

Copyright © 2006 by World Economic Forum, (CC BY-SA 2.0) at: http://commons.wikimedia.org/wiki/File:Angelina_ Jolie_at_Davos2.jpg.

Breast Cancer Most people are aware of breast cancer. Most recently (actually today, May 14, 2013, the day I am writing this) the famous actress Angelina Jolie announced she had undergone a double mastectomy (both breasts removed) to reduce her risk of breast cancer. Removing breast tissue is an effective way to reduce risk, but it is also a difficult and drastic step for most women to take. While not as effective as surgery, regular exercise has been shown to decrease the risk of breast cancer in women between 10–30 percent.2

How Does Exercise Help? There are at least two ways that exercise helps to reduce the risk of breast cancer. Similar to colon cancer, the exercise-induced decrease in TGF activity means that cancerous cells that do emerge are more likely to be handled by the body’s natural defenses before they become a problem. The other mechanism of action

2  A. H. Eliassen, S. E. Hankinson, B. Rosner, and W. W. C. Holmes, MD. Physical activity and risk of breast cancer among postmenopausal women. Arch Intern Med., 2010; 170(19): 1758–64.

Colon, Breast, and Maybe Lung Cancer  |  39

for exercise is the effect it has on a woman’s production of the hormones collectively known as estrogens. Estrogens are naturally occurring steroidal hormones that are linked to the female reproductive cycle (we typically refer to the group of estrogens simply as estrogen without the “s”). When girls sexually mature and begin their menstrual cycles, they start to produce large quantities of estrogen during certain phases of their cycle. Because estrogen is a steroid, a class of hormone that promotes cell growth, when a woman’s body is exposed to cyclical increases in estrogen, cells can grow faster. Breast cancer tumors are particularly sensitive to estrogen and grow more rapidly when lots of estrogen is available. Women who exercise regularly decrease the amount of estrogen their bodies produce. Over the course of decades, this reduction in estrogen exposure lowers breast cancer risk. Researchers are also investigating the effect exercise may have on estrogen metabolism (how quickly estrogen is broken down in the body). While these data are preliminary and have not provided a clear picture, it is possible that regular exercise results not only in lower peak levels of estrogen, but also lower exposure time to the hormone, due to increased metabolism. Whatever the case, over the course of a lifetime, physically active women will be exposed to lower levels of estrogen, which decreases their breast cancer risk.

Cancer Summary There is clear and conclusive evidence that exercise reduces the risk of colon and breast cancer. For colon cancer, increased removal of waste from the body, and for breast cancer, decreased exposure to estrogen, are important mechanisms of action. For both, decreases in TGF activity play a role in slowing the growth rate of tumors. In the title of the chapter, I referred to lung cancer. Whether or not exercise can help reduce the risk of lung cancer in current smokers, former smokers, or never smokers is still unclear, but recent attention has been paid to the limited scientific research in the area. Results from two meta-analyses (statistical studies that pool different research data together and compare their results) suggest that there is a possible connection.3,4 Of course, not smoking is the best way to lower your lung cancer risk. 3  L. M. Buffart, A. S. Singh, E. C. van Loon, H. I. Vermeulen, J. Brug, and M. J. Chinapaw. Physical activity and the risk of developing lung cancer among smokers: A meta-analysis. J Sci Med Sport., Mar 22, 2013. Mar pii: S1440–2440(13)00047–9. doi: 10.1016/j.jsams.2013.02.015. (E-pub ahead of print.) 4  J.-Y. Sun, L. Shi, X.-D. Gao, S.-F. Xu. Physical activity and risk of lung cancer: A meta-analysis of prospective cohort studies. Asian Pacific Journal of Cancer Prevention, vol. 13, 2012: 3143–47.

40  |  Why Exercise is Important

I leave a question mark next to lung cancer because there is not enough scientific evidence to give a clear indication that exercise lowers risk. However, given what we know about exercise and tumor-promoting growth factor, it would not be surprising to learn sometime in the future that physical activity helps reduce the risk of other forms of cancer besides colon and breast.

6

Osteoporosis

O

steoporosis is a disease of the bone (osteo-) that is characterized by thinning of the calcified bony structures which provide the solid support network that makes your bones strong. Bone is an interesting substance. When you look at highly magnified images of bone (below), you can see that

Normal bone.

Osteoporotic bone.

Courtesy of Tim Arnett.

Courtesy of Tim Arnett.

41

42  |  Why Exercise is Important

bone is not a solid mass of calcium, but actually a honeycomb structure, much like a bee hive. The picture on the left shows healthy bone from a vertebra of a 30-year-old woman. The picture on the right shows osteoporotic vertebral bone from a 70-year-old woman. Compare the two pictures. What do you notice? Most glaringly, the bone on the right has huge gaps and broken pieces. The actual bony bits that connect to form the walls of the honeycomb are called spiculae. As we age past about 50, our spiculae begin to get thinner and thinner. Eventually, the spiculae can get so thin and the bone so weak that we are diagnosed as having osteoporosis. Bone thinning is a normal aging process, just like atherosclerosis (clogging of your arteries). You probably can’t prevent it, but you can slow it down. In fact, if you do the proper type of exercise while you’re young, you can make your bones so thick that it will take many years once you start losing bone mass before your bones get too thin. This is one of the keys to osteoporosis prevention, and it is only available when you are young and your body is still increasing your bone mineral density.

You ARE at Risk, Particularly Women If you’ve heard of osteoporosis at all, it was probably in conjunction with a discussion you had with or about an older adult because osteoporosis usually doesn’t affect people until they are in their 60s. It’s fair for a young person to ask, “Why should I worry about that now?” The answer is, “Because actions you take now can help lower your risk for osteoporosis 40 years from now.” According to the National Osteoporosis Foundation, as many as one in every two women and one in four men will suffer a fracture related to osteoporosis during their lifetimes.1 Women are at greater risk than men for developing osteoporosis because of several factors: 1. Women are smaller than men = less gravitational and ground reaction force stress on their bones. 2. Women engage in less lifting and other physical activity that stresses their bones, particularly when they are young = lower peak bone mineral density (BMD). 3. Women go through menopause = reduced ability to absorb calcium into bones.

1  http://www.nof.org/files/nof/public/content/file/63/upload/49.pdf, p. 6.

Osteoporosis | 43

While osteoporosis does not directly kill you, people who suffer fractures due to this disease suffer many negative consequences, including reduced quality of life, loss of mobility, and in some cases, death, due to factors related to their fractures.

How Does Exercise Help? In order to understand how exercise helps, you have to first understand a little bit about bone construction. There are two types of bone cells that are responsible for building and maintaining healthy bones: osteoblasts and osteoclasts. Osteoblasts are the builder cells (“b” for blast and builder), while osteoclasts are the demolition crew. As we grow, osteoblasts are busily gathering calcium from our blood and using it to form the cement which creates the spiculae. Year after year, as we grow taller, more and more calcium gets accreted into our bones. The bones get bigger and thicker. Our skeleton grows. At the same time, because bone is a dynamic, living structure that can suffer injury, the osteoclasts are busily breaking down damaged bone and sanding the surface, so when the osteoblasts come to lay down more “cement,” there will be a healthy layer of bone available to accept the new calcium. Osteoblasts build, build, build, and osteoclasts remove, remove, remove. This process goes on constantly for as long as you live. When you’re young, the rate at which the osteoblasts work far exceeds the rate of the osteoclasts, so your bones get bigger, thicker. For most humans, somewhere around 25 years of age, their skeletons stop growing. At this point, the osteoblasts slow down and now only build as much as they need to replace the damaged bone that is being stripped away by the osteoclasts. This equilibrium exists until about age 50, at which point the osteoblasts slow down further, while the osteoclasts continue to absorb damaged bone. The net result: bone loss. Exercise provides different benefits, depending on a person’s age. For young people (under 25 years old), the importance of exercise is that it drives calcium into your bones, increasing bone mineral density (BMD). Think of BMD as a retirement account. The more exercise you do (without overdoing it), the more calcium you store in your bones, like putting money into a retirement account. The retirement age for your skeleton is about 50, so once you hit that point, you start depending more and more on the calcium you saved when you were younger to keep your bones healthy. If your savings are small, and your life long, you will very likely develop osteoporosis. For someone in young adulthood through middle age (25–50), exercise helps to maintain adequate stress on the bones so that BMD stays consistent, and in older age (50+), exercise helps to slow down (and perhaps even halt) bone mineral loss.

44  |  Why Exercise is Important

Specifically how exercise does this is related to a concept from physics called the piezoelectric effect. This concept states that when some materials are compressed or stressed, they are capable of producing electric current. Bone is a piezoelectric material, so when enough force is applied (i.e., weight-bearing exercise), it generates some electricity, and this electricity attracts osteoblasts. Osteoblasts arrive at the stressed bone site and begin to lay down calcium to reinforce the stressed surface. In other words, when you overload your skeleton by putting a lot of force on it, your body responds by saying, in effect, “I better make this bone stronger so it doesn’t break the next time it gets stressed.”

Osteoporosis Summary Exercise that places stress on your skeleton, like weight lifting or running, makes your bones more dense when you are young, and preserves that density as you age. If you are a woman, particularly a petite woman, you should lift weights to apply enough stress to your skeleton to create and preserve bone mineral density. Walking and running will help your legs, hips, and lower spine, but not your upper body. When I go to a fitness center, I often see many young women doing cardio and young men lifting weights. In fact, from a health perspective, these activities should be reversed. Young men need more cardio to protect their arteries because they don’t have the protective hormones young women have. Young women should be lifting weights to make their bones as strong as possible. If you are not yet 25 years old, you still have time to add to your bone mineral savings account. Stress your skeleton!

iv. WitnEssEs fOr thE dEfEnsE Now that I’ve laid out evidence that demonstrates the important relationship between physical activity and health (and hopefully convinced you that exercise is an essential component of a healthy lifestyle), we move to the second phase of the argument. In court, this would be the prosecutor presenting her witnesses. For us, it will be a three-chapter explanation of “What and How Much Should I Do?” as a way of prosecuting a sedentary lifestyle. We will review basic exercise science information that provides context to an exercise prescription, and then discuss exercise guidelines established by the American College of Sports Medicine, an international organization with a long history of providing scientifically based exercise advice.

45

7

Cardiorespiratory Exercise

C

ardiorespiratory exercise, or cardio for short, is any type of exercise that relies primarily on oxygen to metabolize fat or sugar into energy. Common forms of cardio include walking, running, cycling, swimming, and using an elliptical trainer. All of these exercises have at least one thing in common—they engage large muscles in repetitive, rhythmic motion.

The Exercise Science of Cardio Changes in the human body can be dramatic once someone starts doing cardio, particularly as the exercise intensity increases from moderate to vigorous levels. The purpose and importance of those changes can be summarized in two words: oxygen demand. In order for your muscles to be able to do work, they must have energy. The basic unit of energy in the human body is called ATP (adenosine triphosphate). Your body has several ways to produce it, but during cardiorespiratory exercise, the most important system is known as the aerobic energy system (also called the Krebs Cycle and Electron Transport Chain, a term you may remember from high school biology). The word aerobic means “with oxygen,” and the aerobic energy system requires oxygen to create ATP. The reason we rely so heavily on the aerobic energy system during cardio is because our ATP demands are very high during those exercise bouts, and this system is the only one capable of producing enough ATP as cardio becomes vigorous. In exercise science, we sometimes gauge ATP demand with a metric called MET—metabolic equivalence. One MET is the amount of oxygen your body 47

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uses at rest, normalized for body weight (this allows us to compare MET values between different people). The actual value of 1 MET is 3.5 ml of oxygen per kg body weight per minute. As exercise intensity increases, MET values 1 MET = the amount of oxygen your increase, reflecting the increased body uses at rest. demand for ATP. While you are sitting reading this book, your MET value is one. When you start walking, that value increases to four (walking can require four times more energy than sitting). If you begin to run, your MET value can increase tenfold. It’s not unusual for a fit, athletic person to have a peak MET capacity of around 15, while elite athletes in cardiorespiratory sports can reach MET values around 20.

What Happens to My Body When I Do Cardio? The physiological changes that happen during exercise are driven primarily by your body’s need to provide more oxygen to working muscle. Here’s a short list of some of the important, short-term changes that occur to get oxygen moving quickly: 1. Adrenalin stimulates the heart to beat faster. a. Resting heart rate for a healthy 20-year-old person can be 65 beats per minute. During moderate intensity exercise, heart rate will increase to 120 beats per minute; during vigorous exercise, 160 beats per minute is easily attained. 2. Brain signals the diaphragm muscle under the lungs to contract more rapidly, increasing breathing rate. a. Resting pulmonary ventilation (breathing rate) can be 15 breaths per minute. During vigorous exercise, that rate may reach 40–50 breaths per minute. 3. Arteries and veins expand to accommodate increased blood flow. When you begin a new cardio exercise routine, you’ll notice other changes happening over the long term. Most notably, it will become easier. The same routine that used to make your heart race and you gasp for breath will soon become manageable, even easy. You’ll find you have to increase the exercise load (by increasing the grade or speed on your treadmill, for example) if you want to get a vigorous workout. These changes can be attributed to two things—an

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increase in your body’s ability to utilize oxygen and an improvement in its ability to remove heat.

Oxygen Utilization Increases Several physiological changes occur with training that allow you to use more oxygen. This increases your ATP production, permitting you to do more work. These changes include:

A Stronger Heart The muscle tissue of the heart, reacting to the demand that it beat faster, will get stronger and more efficient. As a result, every time your heart beats, it is able to push more blood out of its chambers and into the body. The percentage of blood ejected from your heart with each beat is called the ejection fraction. Doing cardio increases your ejection fraction. Cardio is resistance training for your heart muscle.

More Red Blood Cells Red bloods cells (RBCs) are the oxygen-carrying components of your blood volume. Assuming adequate amounts of iron are present, RBCs pick up oxygen molecules as they travel past the lungs. If you have more RBCs in your blood, you are capable of carrying more oxygen away from the lungs. In athletics, adding extra red blood cells to your body is a form of cheating known as blood doping. Doing cardio increases the number of RBCs in your blood.

More Mitochondria A mitochondrion (singular) is the cellular organelle responsible for creating aerobic energy. A single cell can have many mitochondria. Oxygen and byproducts of sugar and fat metabolism enter the mitochondria, where they go through the Krebs Cycle and Electron Transport Chain. ATP is created. As you do cardio training at higher and higher intensities, your body builds more mitochondria so you can produce more ATP.

More Aerobic Enzymes Enzymes are substances that assist in making chemical changes in your body. In addition to making more mitochondria, your cells create more enzymes that are needed to allow the mitochondria work at peak efficiency.

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Heat Removal Improves One of the by-products of ATP creation is heat. If your body gets too hot, you can suffer serious health consequences, such as heat stroke. As your body heats up, your brain monitors this heat stress and when the stress gets too high, the brain sends signals that make you feel unwell—your body’s way of getting you to slow down and decrease your heat production. Several physiological changes occur with training that make it easier for your body to get rid of heat through either evaporation (heat pulled from your body to change water from a liquid to a gas) or radiation (heat moving out of your body from an area of higher concentration to an area of lower concentration).

More Capillary Beds under the Skin (Improved Radiation) Capillaries are the fine end points of arteries, part of our blood transportation system. With regular exercise, your body creates more capillaries near the surface of the skin, and those capillaries will dilate more. This allows hot blood to get close to the air outside your body, and assuming it is hotter inside your skin, heat will move from the area of higher concentration to lower concentration, radiating into the environment.

Increased Water Storage in the Blood (Improved Evaporation) Blood volume can increase as much as ten percent with training,1 driven primarily by an increase in water retention. Having more water available allows you to sweat more without becoming dangerously dehydrated.

More Dilute Sweat (Improved Evaporation) People who exercise regularly store more water in their blood, a sort of sweat reservoir. One effect of this extra water storage is that it makes your blood more dilute (more particles of water per volume of blood). When you sweat that water out, the sweat is more dilute (fewer particles of minerals per volume of water). Dilute sweat is easier to evaporate, which makes it a more efficient heat disperser.

Increased Sweat Rate (Improved Evaporation) At rest, your sweat rate is negligible, assuming a temperate environment. During moderate exercise, sweat rates can reach 1000 milliliters/hour, and 1  M. N. Sawka, V. A. Convertino, E. R. Eichner, S. M. Schneider, and A. J. Young. Blood volume: Importance and adaptations to exercise training, environmental stresses, and trauma/ sickness. Med. Sci. Sports Exerc., vol. 32, no. 2, 2000: 332–348.

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during vigorous exercise, you might sweat as much as 1500 milliliters/hour. People who exercise frequently sweat more, which allows them to lose more heat due to evaporation.

Sweating Starts Sooner (Improved Evaporation) People who train will begin sweating more immediately. This reduces the amount of heat that gets stored in the blood during the early stages of exercise, reducing the risk that the body gets overheated.

Cardio Exercise Science Review When you engage in cardio, you are turning on your body’s large ATPproducing factories which require oxygen to run. The more oxygen your body can absorb into the blood and process in the mitochondria, the more ATP you can make—and the easier cardio gets. Getting rid of excess heat also makes cardio easier. This happens through improved evaporation of sweat and heat radiation through the skin.

How Much Cardio Should You Do? (Based on American College of Sports Medicine (ACSM) Guidelines) When giving exercise prescriptions, fitness professionals commonly use the FITT acronym to remind them of all the recommendations to follow. • F = Frequency • I = Intensity • T = Time • T = Type

Frequency Although ACSM guidelines do not explicitly state you should do cardio more than once a week, I believe multiple days per week is an important part of a healthy exercise prescription. This personal recommendation is based on the fact that some of the chemical changes that occur in your body when you exercise only last for hours before they return to baseline. Your blood pressure response to exercise is a good example of this. It goes up while you are working out, goes below baseline when you stop, and returns to your regular score within a few hours. If you only do cardio once a week, you only change your chemistry once a week, which may be too infrequent to promote robust health benefits.

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ACSM’s guidelines for frequency are: F: One or more days a week, accumulating 75 minutes of vigorous activity, or 150 minutes of moderate activity. I would recommend three or five days a week, vigorous or moderate intensity, respectively.

Intensity and Time Intensity and time are interdependent, so we’ll discuss them together. First, let’s talk about intensity. There are two exercise intensities that are beneficial to your health—moderate and vigorous. Moderate intensity exercise is the type of exercise you can do while being able to speak at least a few sentences to a friend without feeling the need to take a breath. On a personal scale of one to ten, your exertion should feel like a five or six. A more clinical definition would be exercise that increases your heart rate to Maximal Heart Rate = 220 - Age between 50–70 percent of your maximal 2 heart rate. For a 20-year-old, that range would be 100–140 beats/minute. Vigorous intensity exercise requires you to take breath after only a few words, instead of a few sentences. On a personal scale of one to ten, your exertion should feel like a seven or eight. Using target heart rate range, you should be within 70–85 percent of your maximum, which for a 20-year-old is 140–170 beats/minute. If you choose to exercise at a July 12 moderate intensity, you need to do at least 150 minutes a week of Cardio Prescription Review cardio for it to have enough effect F: 3 or 5 days/week on your body to reduce your risk of i: vigorous or moderate dying prematurely by 50 percent. T: 25 or 30 minutes Using my advice of five days per T: Continuous movement for at least week for frequency, the time for 10 minutes each workout becomes 30 minutes (30 × 5 = 150). When you increase the intensity to vigorous, the time requirement decreases to 75 minutes a week. You could fulfill this requirement by exercising for 25 minutes three days a week. So, using the FITT acronym, intensity and time recommendations are: 2

http://www.cdc.gov/physicalactivity/everyone/measuring/heartrate.html

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I: Vigorous or moderate T: 75 (vigorous) or 150 (moderate) minutes/week minimum.

Type According to ACSM, a bout of cardio must last at least ten minutes and be at least moderate intensity; the activity must get your heart rate to 50 percent of your maximum and hold it there. Cardiorespiratory exercise typically engages large muscles groups and has them work in rhythmic fashion. Examples of cardio are walking briskly, running, biking, swimming, and dancing. T: Rhythmic movement that involves large muscle groups and is at least ten minutes long.

Components of a Safe Cardio Workout All exercise includes some risk. For example, it is estimated that for every 200,000 exercise bouts apparently healthy people do, one will result in sudden death.3 On a less extreme scale, it is not unusual for someone to sprain a joint or strain a muscle when working out. Here are some ways to reduce your risk.

Warm Up before Working Out (Three to Five Minutes) Before you engage in a vigorous bout of exercise, you should ease your body into it by engaging in a lower-intensity version of the activity you are about to begin. If your preference for cardio is running, begin by walking at a brisk pace or jogging at a slow pace before you increase the speed of the treadmill. This prepares your body for the tremendous stress vigorous exercise places on it (ground reaction forces against your feet can be three times your body weight during a run). From a lifetime health-and-fitness perspective, perhaps the most important reason to warm up is that it prepares your joints to handle stress by promoting the release of synovial fluid into the joint cavity. This has a protective effect on the cartilage that covers the ends of bones in a joint. Note: Stretching does not equal warming up!

Apply the Principle of Progression If you are new to exercise, don’t expect to be able to perform like a veteran. Vigorous exercise (jogging +) can be very challenging for an unfit individual, so

3  Engelstein ED, Zipes DP. Sudden cardiac death. In: Alexander RW, Schlant RC, Fuster V, eds. The Heart, Arteries and Veins. New York, NY: McGraw-Hill; 1998:1081–1112.

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even if you are young and apparently healthy, your performance will be limited by your body’s ability to produce ATP. An exercise novice, regardless of age, won’t be able to produce very much ATP easily. If you start your exercise bout at a high intensity, it probably won’t last very long. If it doesn’t last at least ten minutes, it doesn’t count toward the ACSM cardio prescription. Start slowly. Most beginners should begin by walking at 3–3.5 miles per hour (even this may be too fast for a very deconditioned person). If you are using a quarter-mile track at your local high school, it will take you 17–20 minutes to complete a mile (four laps) at this pace. Increase your speed as your body adapts to your new activity program. If you can walk at 3.5–4 miles an hour without getting out of breath while sweating only lightly, then you may want to increase the workload. Try jogging at 5–6 miles an hour.

Remain Hydrated You can lose several pounds of water during a vigorous cardio workout. Since water is needed for heat dispersal, it’s important to make sure you replace water lost during exercise. Current guidelines say the best way to gauge how much you need to drink after a workout goes like this: 1. Weigh yourself naked before workout; 2. Weigh yourself naked after workout (clothes will have absorbed some sweat); 3. Drink in liquid ounces the number of weight ounces lost. Since there are 16 ounces in a pound of weight, if you lost two pounds of weight, you should drink 32 ounces of water.

Cool Down Actively (Three to Five Minutes, HR 80 percent 1-RM. Generally speaking, an appropriate amount of weight to lift seems relatively easy when you are starting a set, but difficult by the end of it.

Time All levels of weight lifters have the same minimum prescription: one set of 8–12 repetitions.1 Each repetition should take two to four seconds to complete. This implies that you need to be in control of the weight, both when you are moving it against the force of gravity, as well as when you are moving it with gravity. Controlling the descent of weight when gravity is pulling on it is known as “working the negative.” If you disengage your muscle when gravity starts helping, you miss out on approximately 50 percent of the work time you could be stimulating your muscle fibers. Work the negative.

Type The only specific guidelines ACSM gives regarding type is to say you need to work all major muscle groups. So, whether you go to a weight room and lift 1  NOTE: This is a minimal prescription designed to protect health. If you want to see significant gains in muscle mass, you must do more.

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Copyright © 2013 by Depositphotos / Stihi Valeriu.

weights, do a Pilates-type yoga class, or your own set of calisthenic exercises utilizing your body weight as resistance, you need to train the shoulders, front and back arms, the chest, back, abdominals, front and back thighs, and back lower legs. Because your legs are accustomed to lifting your body weight already, if you want to make marked improvements in leg strength, you probably need to go to a weight room. Most people who strive to increase muscle mass and accrue large gains in strength do weight lifting.

Components of a Safe Weight-Training Workout Weight training can be a potentially dangerous activity because you are manipulating tens or even hundreds of pounds of weight. Move the wrong way, use

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improper form, or lose control of the weight, and injury can occur.2 While it is very rare, people have died from accidents involving weight-training equipment.

Warm Up Before Working Out July Warming up before lifting is as 12 important as warming up before cardio. In the case of heavy weight Resistance Training Prescription lifting, warm-up should involve Summary two phases. The first phase, which F: Two to three days/week all weight lifters should engage in, i: 60–70 percent 1RM (novice, is a general whole-body warm-up intermediate) or > 80 percent 1RM similar to what you might do (advanced) before cardio. Walk on a treadmill T: One set, 8–12 reps, 2–4 seconds/ for three to five minutes. This rep increases your heart rate and T: All major muscle groups prepares your joints for stress. The second phase would be a low level of activity mimicking the lifts you are about to engage in. If you are going to do squats, perform a set using moderate weight. This allows your neuromuscular coordination to engage fully before you ask your muscles to exert a near-maximal contraction. You will perform better (have better form and perhaps execute more reps) if you do a warm-up set of exercises.

Apply the Principle of Progression For a novice, a weight room can be very intimidating. There are foreignlooking pieces of equipment. People engaged in weight training are usually very focused, so they can appear uninviting. Begin with a tour of the facility guided by a friend or staff member. You should be shown how all of the machines function, including how to adjust them for your body size and how to change the weight. In some cases, you can also manipulate the range of motion (how far and in what plane you can move the machine).

2 Z. Y. Kerr, C. L. Collins, and R. D. Comstock. Epidemiology of weight training-related injuries presenting to United States emergency departments, 1990 to 2007. Am J Sports Med., Apr 2010:; 38(4): 765–71. doi: 10.1177/0363546509351560. (E-pub. Feb. 5, 2010.)

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Focus first on mastering the weight-training machines, then progress to dumbbells and other free weights. Machines and free weights have advantages and disadvantages that mirror each other. The primary advantages of machines are: 1. Machines are very safe. The weight you are moving does not directly touch your body, so if you lose control, the weight usually doesn’t fall on you. 2. Machines guide you through a movement pattern, facilitating learning. As you repeat the movement pattern, your body establishes a muscle/motor unit activation pattern that you will rely on to do the movement in the future. 3. Machines are quicker. Because you do not have to manipulate individual dumbbells or weight plates (which should be returned to their original storage space immediately after you are finished with them), a machine-based weight training routine will usually be completed more quickly. While there are no strictly established guidelines for how long you should spend on machines before progressing to free weights, I suggest spending at least four to six workouts on machines. However, once your body has adapted to your new weight-training program, you should incorporate some free-weight exercises into your workout. The advantages of free weights include: 1. More muscles are involved. Take, for example, a shoulder press exercise, where you lift weight above your head. Doing this exercise with free weights

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engages stabilizing muscles responsible for keeping your arms moving in the correct plane of motion. These muscles don’t need to work if you are using a machine. 2. More realistic. Doing exercise with free weights allows you to adjust your movement patterns to your preference. Some bodies move differently from others, and machines can’t always accommodate that variation. If you’re an athlete, you probably want to move your body against resistance in many different ways to mimic your sport movements.

Copyright © 2012 by Depositphotos / nelka7812.

A final word about progression. A novice should begin with relatively light weight (perhaps less than what ACSM recommends). For some complicated and relatively riskier exercises like squats, you might begin with nothing but your own body weight as you learn proper technique.

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Train with a Partner This is important if you are using free weights and performing heavy lifting. Remember how muscle fibers are controlled by toggle switches? When they work very hard and become exhausted, those toggle switches get flicked off. In your house, flicking the light switch off throws you into complete darkness. In the weight room, flicking the switch off causes you to immediately drop the weight. If you are performing an exercise like a bench press where the weight is over your body, you need to have a spotter in place to help prevent or reduce severity of injury that could occur if you lose control. DO NOT LIFT HEAVY WEIGHTS WITHOUT A SPOTTER.

Exhale during the Heavy-Lifting Phase (Usually When Moving against Gravity) When you engage in weight training, your blood pressure can easily double. If your normal systolic blood pressure is 120, it could increase to 240 during a lift. If you hold your breath when you lift, the blood pressure response is even higher, with systolic blood pressure scores potentially exceeding 300. This is a lot of stress on your arteries and veins and increases your risk for stroke and hemorrhages. Exhale during the heavy-lifting phase to reduce these large blood pressure responses.

9

Flexibility Exercise

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lexibility training, commonly referred to as stretching, increases muscle length, which improves joint range of motion. Maintaining flexible joints may be of particular importance in older age, to allow for maintenance of activities of daily living. Flexibility-related exercise regimens like yoga and tai chi also contain a relaxation component that may help control stress and anxiety.

Flexibility Training Exercise Science From an exercise science perspective, flexibility refers to the range of motion (ROM) available to a joint. A joint is a place where two bones meet. Some, like the ball-and-socket joints of the hips and shoulders, are very flexible because of their design. Other joints have no flexibility (think bony plates of the skull). Flexibility is controlled by several factors.

Genes Women are more flexible than men. Can you identify a sex-specific difference that would require more flexibility in women?

Skin and Connective Tissue (e.g., Tendons and Ligaments) Surrounding the Joint Joint laxity refers to the amount of stability in a joint. Healthy joints have normal amounts of joint laxity. As we injure tissue around the joint—for example, 65

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sprain the ligaments of the ankle playing basketball—joint laxity increases. This is usually an undesired form of flexibility because lax joints are more easily injured again.

Scar Tissue When the tissue around a joint gets injured, the body creates scar tissue to limit movement of the joint. This facilitates normal healing. Once the area is healed, however, scar tissue is not automatically reabsorbed by the body. One of the primary purposes of physical therapy after joint injury is to break up scar tissue, which, combined with proper muscle strengthening, returns normal ROM.

Age As we age, connective tissue surrounding joints becomes less elastic and more plastic. This can restrict ROM. Older people are also more likely to have suffered injuries to joints, and the cumulative effect of those injuries could reduce ROM. Muscle weakness is a third age-related factor that could reduce joint movement. Also, older people tend to move less.

Disuse Sedentary people tend to become less flexible because they don’t move their joints through full range of motion very often. One of the quirks of muscle physiology is that the contractile proteins we discussed in the resistance-training chapter are unidimensional in the way they work. When a motor unit gets activated, the contractile proteins pull themselves closer together. This muscle shortening, referred to as the sliding filament theory of muscle contraction, is the only active way contractile proteins can move. In order for the muscle fibers to be returned back to their original length, an external force has to be applied to the muscle. This usually happens when the joint is moved in multiple directions and opposing muscles groups (think triceps and biceps) alternate action. Gravity can also provide the force to return muscle fibers to their starting position. Sedentary people tend to exert force mostly in a single direction (generally speaking, reducing joint angles), and they experience loss of flexibility over time.

How Does Stretching Increase Flexibility? Stretching can’t change your genetic makeup, reverse your injury history, or stop the age-related changes to your connective tissues. It may help break up scar tissue. But the single most important way stretching helps to improve

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flexibility is a result of training small components in your muscles and tendons, known collectively as stretch receptors.

Stretch Receptors Your body has several types of stretch receptors, including Golgi tendon organs and muscle spindles. As the names suggest, the first type are located in tendons (connective tissue that links muscle to bone) and the second in muscle bellies. The purpose of these stretch receptors is to provide feedback to the brain about body movement. Have you ever wondered why you can close your eyes and still perform a relatively complicated movement, like walking up a flight of stairs? How are blind people able to navigate the world? An important component of these abilities comes from the information provided by stretch receptors. Let’s consider a muscle spindle. Muscle spindles are embedded in the belly of a muscle. When a muscle contracts, the spindle shortens. This change in length is transmitted to the nervous system, where the brain uses it to figure out how much our bodies are moving. Taking input from many receptors, the brain is able to create a map of our movement. It knows that when muscles A, B, and C activate Y percent of their motor units, your foot will rise three inches in the air. Stretch receptors are the way the brain understands your body’s position in space. The fancy word for this is proprioception. Muscle spindles are a key element of proprioception.

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To answer the question posed at the beginning of this section, we first have to consider why you don’t move your joints as far as they could possibly go. Let’s use your legs as an example. Hips are ball-and-socket joints that are potentially very flexible. When you were a child, you could probably bring your foot behind your head if you wanted to. Most of us can’t do that now. Why not? This isn’t a trick question. The simple answer is, “It hurts—a lot.” The reason people stop moving a joint when they are stretching is because it starts to hurt. Boiled down to its essence, gaining flexibility is learning how to overcome those pain signals.

Where Do Pain Signals Come From? Your brain is responsible for communicating pain, and it does this when you move muscle spindles beyond their “normal” length. In this context, “normal” refers to the usual range of motion a muscle spindle goes through as a muscle contracts and relaxes. Let’s think about the legs again. If all you do with your legs is walk, you’ll be lucky to move your hips through about 30 degrees of motion. This is your “normal.” Lie on your back and lift your leg, and once it goes past 30 degrees, you’ll start to experience discomfort. Go far enough, and that discomfort becomes pain. The pain goes away once you show your body that moving the muscle spindle to a new, more stretched-out position will not harm you. In order to retrain the brain, to get it to interpret a new muscle spindle position as the new “normal,” you must keep the muscle spindle stretched for some seconds, perhaps as long as 30 seconds. Holding a stretch allows the brain to understand that having a muscle spindle move through a greater range of motion will not result in harm. Therefore, when you go to move this way in the future, your brain will not tell you, “It hurts!” Pain diminishes—and you become more flexible.

Forms of Stretching There are several different ways to stretch. We will review three common forms here and compare them across two variables: effectiveness and safety.

Ballistic Stretching An example of a ballistic stretch is a runner leaning with hands against the wall, one leg back, bouncing up and down on the ball of his back foot. He is rapidly and repeatedly stretching the muscle and connective tissue of his foot and calf. This is perhaps the least safe way to stretch, particularly if it occurs before the run, since rapid, heavy loading to tissue that has not warmed up may cause

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damaging tendon sprain or muscle strain. More importantly, if you are trying to increase your flexibility permanently (i.e., get your brain to stop sending pain signals), ballistic stretching does not keep the stretch receptors held in the elongated stretch position long enough for learning to occur. • Ballistic stretching is the least safe and least effective way to permanently increase flexibility.

Copyright © 2012 by Depositphotos / STYLEPICS.

Static Stretching The same runner’s calf stretch done where the heel of the back foot stays on the ground the entire time is an example of static stretch. If you hold this position long enough (see flexibility prescription guidelines below), you can gain a permanent increase in flexibility. This form of stretching is very safe because you can tell when you are exerting too much strain on your calf, so overstretching is unlikely to occur. It is also an effective way to improve flexibility. • Static stretching is the safest way to stretch.

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Proprioceptive Neuromuscular Facilitation (PNF) PNF requires a partner to do it effectively, and involves periods of muscle contraction followed by relaxation and stretch. The hamstrings, muscles of the back of the thigh, are often targets of this type of stretching. A PNF hamstring stretch would go something like this: 1. The person being stretched lies on her back and the training partner lifts her leg (knee straight) to the point where she begins to Safest Most Effective feel discomfort. 2. The training partner braces 1. Static 1. PNF her leg to prevent it from 2. PNF 2. Static moving back toward the 3. Ballistic 3. Ballistic ground while the woman on the ground pushes as hard as possible against the resistance for three to five seconds. 3. After she relaxes, the partner moves the leg toward her face. This process repeats for two to three cycles. Marked improvements in ROM will occur. At the end of the contract-relax cycles, the leg is held in a static stretch position. • PNF is the most effective way to stretch (particularly when combined with static stretching), but because a second person is involved, it may not be as safe as static stretching.

Flexibility Training Exercise Science Review Your muscles contain stretch receptors called muscle spindles. When those stretch receptors are extended or compressed, they emit information your brain uses to determine your body’s position in space. Disuse makes muscles tighten up. In order to safely and permanently increase joint flexibility, the muscle spindles need to be stretched beyond their normal distance and held in place for tens of seconds. This training of the muscle spindles results in improved flexibility. Static and PNF stretching are safe and effective ways to increase flexibility. Combining the two techniques may be the best way to gain large and permanent increases in flexibility. Ballistic stretching is not a first choice because the

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risk of injury may outweigh the short term benefits it conveys, and it does not result in permanent improvement in flexibility.

How Much Resistance Training Should You Do? (Based on ACSM Guidelines) Frequency Adults should engage in flexibility training two to three days a week.

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Flexibility Training Prescription Summary F: Two to three days/week i: To the point of discomfort, not pain or quivering T: Two to four sets, one rep, 15–30 seconds per rep, totaling 60 seconds for each muscle T: Static, all major muscle groups.

Intensity The stretch should be taken to the point where tightness and mild discomfort begin. If the pain is sharp, or the muscle begins to quiver uncontrollably, lower the intensity of the stretch. During the stretch, if the muscle relaxes to the point where tension disappears, slowly take up the slack by stretching a little further.

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Time Each stretch should last 15–30 seconds, repeated two to four times. Accumulate a total of 60 seconds of stretch time for each muscle. It is better to stretch after a cardio or resistance-training workout than before the exercise bout, since muscles will be warmer. Type All muscles controlling joints where you desire greater flexibility should be stretched. Static stretching is safe and effective and requires no assistance, making it a practical choice. Other forms of stretching are also effective (see above), but you can easily practice relaxation techniques during static stretching, which may help reduce stress and anxiety.

Components of a Safe Flexibility-Training Workout Don’t Overdo It The primary safety concern for stretching routines is overstretching. There are some people who require very flexible joints, like gymnasts and contortionists. These people compete and make livings in part by relying on extraordinary range of motion. Most people don’t need that degree of flexibility, and there are some joint components that should not be stretched. Ligaments, which connect your bones together, are a prime example. The consistency of ligaments is somewhat like the plastic that makes up a milk container. Those containers are very strong, but once you deform them, they will never return to their normal shape. Once you stretch a ligament, it will permanently remain longer. This increases joint laxity, which increases the likelihood the joint will be injured in the future.

Maximize Your Stretching Time The research on stretching is sparse and inconclusive. From a health perspective, there is no consistent scientific evidence that regular stretching is important for your well-being, particularly in young people. It may be important for older adults. To make the most of the time you spend stretching, it may be useful to focus on stress reduction, in addition to performing stretches. A simple and effective way to reduce physical stress is controlled, deep breathing. Eastern forms of flexibility-related exercise regimens such as yoga emphasize the importance of breathing technique. From a scientific perspective, slow, deep breathing has a direct physiological effect on your stress levels. This is because the muscle that

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controls your lungs (the diaphragm) has both a conscious and subconscious connection to your brain. When you are stressed, breathing rate increases. This is a typical response to cardiorespiratory exercise, as well as to fear and excitement. This increase in respiration is subconscious, controlled by the autonomic nervous system. It is your body’s way of preparing to exert muscle force you may need to protect yourself. • Stress = faster breathing. What happens, then, if we take conscious control of the diaphragm muscle under the lungs and slow our breathing rate? When we do this, we send signals to the brain to relax. Fast breathing indicates a STRESSED state, slow breathing signals your body to RELAX. By consciously slowing your breathing down, you can lower your heart rate and change the chemistry of your body from a stressed to a non-stressed state. These chemical changes may have important consequences for your health. • Relax = slower breathing.

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To maximize the usefulness of the time spent on your stretching routine, focus on slow, deep breathing. By consciously changing the chemicals being released in your body, you can reduce physical stress, which may lead to reduced anxiety and better health. This focus allows you to not only improve your flexibility through stretching, but may also improve your mental well-being.

v. clOsing argumEnt

By now I hope you are firmly convinced that exercise is essential for maintaining good health, and you have a clear idea how much physical activity you need to get to protect your health. This final chapter is a discussion about nutrition basics. Understanding a little bit about nutrition will help you achieve one very common exercise goal—weight loss and maintenance.

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10

Nutrition Basics

H

uman nutrition is a complicated subject, and a detailed discussion is beyond the scope of this book. However, since many people first begin thinking about adopting a new exercise program as a way to control weight, it is important to understand the basics of nutrition. You will not lose and maintain weight loss simply by adding exercise to your daily routine. Remember, there are 3,500 calories in a pound of fat. You would have to exercise every day of the week to lose one pound of fat. This slow rate of loss will discourage many people. To speed it up, you must consider your diet. This chapter will review the macronutrients of human nutrition (fat, protein, carbohydrate), as well as fiber and water. By the end, hopefully you will understand that choosing the right food to eat is complicated, but not beyond the scope of understanding. You can’t simply say, “No fat, please,” but you also don’t need to know the molecular structure of a triglyceride molecule to get it right.

Carbohydrate Carbohydrate, or carbs, as they’re commonly called, are the instant energy source for the body. One gram of carbohydrate contains approximately four kilocalories, or four kcals (one kcal = the amount of energy needed to raise one kilogram of water one degree Celsius). In nutrition terminology, one kcal = one calorie. Therefore, nutritionists simply say one gram of carbohydrate contains four calories. There are two general classes of carbs: simple and complex.

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Simple Carbohydrate Simple carbs are usually called sugar. Glucose and fructose are two common examples. Sugar’s reputation is stained because many people connect sugar intake with obesity and diabetes. There is no evidence sugar intake causes diabetes. Type II diabetes is influenced heavily by obesity, not sugar consumption. There may be a positive correlation between sugar intake and weight gain/ obesity (eat more, gain more) because it is very easy to eat a lot of sugar quickly, which equals a lot of calories very quickly. One reason we overindulge should i eat fruit? An important in sugar is because the brain likes exception to the “restrict simple carbs” it. Sugar intake stimulates pleasure rule is fruit, which contain high levels centers in the brain, which reinof simple sugars but also contain many forces the desire for more sugar.1 other nutritious substances. Controlling simple sugar intake may If you are trying to lose weight, help slow down weight gain as you be aware of the calorie content of decrease your desire to eat more fruit. Fruit juice is particularly high in calories. sugar. This is one reason nutritionists recommend you limit your intake of simple carbohydrates. Another reason for limiting simple carb intake is because many foods that contain a lot of sugar contain little else of nutritive value. When you eat simple carb foods, you are usually eating junk food or “empty calories,” meaning the food provides some energy, but few vitamins, minerals, or fiber. To control weight gain, you must limit the number of calories you consume. At the same time, you need to get all the nutrients your body requires to function correctly. In nutrition terms, this means you must strive to eat many “nutrient-dense” foods. Foods with many simple carbs usually have low nutrient density, so simple carbs should make up a relatively small percentage of your daily diet.

Complex Carbohydrate Complex carbs, commonly referred to as starches, are a cornerstone of good nutrition. Starches are complex sugar molecules that take longer to digest compared to simple carbs. Grains, nuts, legumes (beans), and vegetables are all examples of complex carbohydrates and should comprise a relatively large percentage of your diet. Complex carbs are nutrient-dense foods, making them an excellent food choice. 1 A. S. Levine, C. M. Kotz, and B. A. Gosnell. Sugars: Hedonic aspects, neuroregulation, and energy balance. Am J Clin Nutr., Oct 2003, vol. 78, no. 4, 834S–842S.

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Complex carbohydrates also contain a lot of fiber, which is another reason to eat more of them. Fiber: • Slows down sugar absorption into your body, which may decrease your urge to eat (spikes in blood sugar are followed by rapid dips that may stimulate appetite). • May absorb LDL cholesterol (the bad kind) in the gut before it enters your bloodstream. • Provides bulk in the stomach, an important cue for signaling you are full. • Helps to maintain regular bowel movements, eliminating potentially harmful substances from your body quickly. Women should consume 25 grams of fiber a day, men 38 grams. An averagesize apple contains about four grams of fiber. Beans (legumes) are a particularly good source of fiber, containing as much as 15 grams per one-cup serving, depending on the type of bean.

Carbohydrate Summary The largest component of most people’s diets around the world is carbohydrate. Your brain uses only carbs for fuel. High-intensity exercise requires carbs. Plants are carbs. Current government nutrition guidelines, as reflected in the myplate.gov picture, suggest that approximately 65 percent of your diet should

Copyright in the Public Domain.

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be carbohydrates (fruits, grains, vegetables) (http://www.choosemyplate. gov/images/MyPlateImages/JPG/myplate_blue.jpg). You should eat more complex carbohydrates instead of simple carbohydrates. Fiber-rich complex carbohydrates are your best choice.

Protein Protein provides the building blocks (amino acids) bodies need to construct new cells. Since our bodies essential amino acids: Body are constantly reforming themselves cannot make them—must be ingested (one estimate is that our cells are, through diet. on average, seven to ten years old),2 nonessential amino acids: Body can create them. adequate protein intake is essential for good health. There are approximately four calories in a gram of protein, but protein is our body’s least preferred energy source. It uses fat and carbohydrate readily to produce ATP, but protein sparingly. Protein can come from both animal and plant products, but each protein source contains different nutrient levels. When nutritionists make recommendations about protein, these other nutrients are a large part of their decision process. Whether you get your amino acids from meat or beans is not terribly important, as long as you get all the essential amino acids (see inset). However, if your protein source has a lot of saturated fat, cholesterol, or salt, it may not be the best choice. If your protein source contains fiber and vitamins, it may be a better choice. Generally speaking, red meat (beef) and full-fat dairy (milk, butter, cheese) are considered second-best protein sources when compared to fish or plant proteins because they contain saturated fat (see the following section on fat for more). Recent research has begun to question whether saturated fat is as unhealthy for us as has been said for decades,3 but even if it turns out that saturated fat is not so bad, nutritionists may still continue to prefer protein sources such as fish (omega fat), and plant protein like nuts and soy beans (unsaturated fat, fiber, vitamins, minerals) instead of red meat and full-fat dairy. Currently, it is recommended that 15–20 percent of our food should be protein. Some popular diets advocate eating more protein, because they suggest 2 A. Heinrichs. Age discrimination. Nature Reviews Molecular Cell Biology 6, Sept. 2005; 672. 3 P. W. Siri-Tarino, Q. Sun, F. B. Hu, and R. M. Krauss. Meta-analysis of prospective cohort studies evaluating the association of saturated fat with cardiovascular disease. Am J Clin Nutr., 2010; 91: 535–46.

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that increased protein will help control food cravings. Research does support that protein has a satiating effect on hunger,4 but it is unknown if eating more leads to even greater reductions in appetite. If you are overeating frequently because you feel hungry often, increasing your protein intake may help. However, replacing fiber-rich, nutrient-dense, complex carbohydrate in your diet with protein may not be the best nutritional choice.

Protein Summary Protein comes from animals and plants. About 15 percent of your diet should be protein. More may help control overeating, but should not be added to your diet at the expense of nutrient-dense foods. Red meat contains saturated fat, generally considered less healthy than most fat (unsaturated) found in plants. When deciding what protein foods to eat, consider the other nutritional benefits of the food. If you are trying to control your weight, consider the fat content of the protein source, as fat contains a lot of energy in a small package.

Fat Fat may be the most misunderstood of the macronutrients. When people hear the word fat, they usually conjure up a negative image. If you get one thing out of this entire discussion on nutrition, it should be that fat is not necessarily bad. In fact, some fat is good. Repeat after me, slowly: Some … fat … is … good. Fat is the energy storage system of the body. One gram contains about nine calories—more than twice as much as the energy content of protein or carbohydrate. Fat does more than just store energy, however. It has several important biological functions, including: 1. 2. 3. 4.

Provides insulation, which helps to control heat loss. Protects internal organs from bruising. Facilitates some vitamin transportation. Provides an important satiety cue.

Of these, the most important in the context of our discussion is number 4: satiety cuing. Satiety is the fancy word for feeling full. When I am satiated by food, I am no longer hungry.

4  D. Paddon-Jones, E. Westman, R. D. Mattes, R. R. Wolfe, A. Astrup, and M. WesterterpPlantenga. Protein, weight management, and satiety. Am J Clin Nutr., May 2008, vol. 87, no. 5, 1558S–1561S.

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Portion Control Controlling how much you eat may be the single most important skill needed to be successful at weight loss and weight control. When people get stomach reduction surgery to help them lose weight, they are working on one of the cues that signals when to stop eating—how full the stomach is. We’ve discussed this when talking about complex carbohydrates and fiber—high fiber foods fill the stomach more, so you eat less. As the stomach distends, stretch receptors in the lining of the stomach are passing information to the brain, which it uses to interpret fullness. Another important cuing mechanism is the amount of leptin in the blood.5 Leptin is a digestive hormone that aids in fat metabolism and when fat is ingested, leptin levels in the blood increase. As leptin levels rise, the brain is signaled that you are getting full, and hunger diminishes. Therefore, eating fat is necessary for proper portion control. Some fat should be a part of every meal, even a salad-based meal. Just as with carbohydrate and protein amino acids, there are different forms of fat, some better for you, some not as good, and at least one form of fat that is dangerous for your health. Understanding the different forms of fat is necessary to make healthy food choices.

Unsaturated versus Saturated Fats Just as protein is made of amino acids, fat is made of fatty acids. Fat saturation is a chemical term that refers to the number of hydrogen molecules attached to fatty acids. Saturated fats have more hydrogen molecules than unsaturated fats. In practical terms, one of the differences between them is that saturated fats tend to be solid at room temperature while unsaturated fats are liquid. Also, saturated fats last longer before spoiling, which make them useful for food manufacturers who strive for a long shelf life in grocery stores. Generally, unsaturated fats are considered better for your health, though as discussed in the section on protein, there is some debate about whether or not the body of scientific research strongly supports that conclusion. Still, many national health agencies and the World Health Organization recommend unsaturated fat as opposed to saturated fat. Saturated fats are generally contained in meat (the solid fat on a steak or piece of chicken) and unsaturated fats in plants (olive oil), so when given the choice, select more plant-based fats versus animal-based fats. 5  M. D. Klok, S. Jakobsdottir, and M. L. Drent. The role of leptin and ghrelin in the regulation of food intake and body weight in humans: A review. Obes Rev., Jan 2007; 8(1): 21–34.

nutrition Basics | 85

Omega-3 Fats There is one prominent exception to the plant/animal fat rule: Fish, particularly cold-water fish like salmon that store a form of fat comprised of omega-3 fatty acids. These fatty acids have received a lot of attention in the health literature, and fish oil is a popular More about fish as a food choice: Larger fishes like shark and supplement in health food stores swordfish may contain high levels of because it contains omega-3s. This mercury. Eat large fishes sparingly popularity is based on some research and smaller fishes frequently. that has linked higher consumption of omega-3s to lower risk for cardiovascular disease. However, a recent, large review of the omega-3 literature reached the conclusion that omega-3s do not prevent disease.6 Still, you will commonly hear omega-3 described as a “good fat,” and some organizations like the American Heart Association recommend it.7 You may try replacing some red meat in your diet with fish. If omega-3 fats are not as healthy as many people think, they may still be less detrimental to your health than saturated fat. Therefore, replacing a saturated fat meal with an omega-3 fat meal could be good for you. Nutritionists generally recommend having fish once or more a week. Besides containing “good fat,” fish is also relatively low in calories and cholesterol, making it a good food choice.

Trans Fats Omega-3s may or may not be “good fats,” but there is definitely “bad fat.” Trans fats are so detrimental to your health (consuming a very small amount increases risk for heart disease significantly) that you should avoid them entirely. The U.S. Food and Drug Administration (FDA) began requiring food manufacturers to list trans fats on food labels in 2006. That same year, a review article in the New England Journal of Medicine discussed how trans fats affect the body. Its findings are summarized below.8 6 E. C. Rizos, MD, PhD, E. E. Ntzani, MD, PhD, E. Bika, MD, M. S. Kostapanos, MD; M. S. Elisaf, MD, PhD, FASA, FRSH. Association between Omega-3 fatty acid supplementation and risk of major cardiovascular disease events: A systematic review and meta-analysis. JAMA, 2012; 308(10): 1024–33. 7 h t t p : / / w w w. h e a r t . o r g / H E A R T O R G / G e t t i n g H e a l t h y / N u t r i t i o n C e n t e r / HealthyDietGoals/Fish-and-Omega-3-Fatty-Acids_UCM_303248_Article.jsp on 5/31/2013 8 D. Mozaffarian, M. B. Katan, A. Ascherio, et al. Trans fatty acids and cardiovascular disease. N Engl J Med., 2006; 354(15): 1601–13.

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Copyright © 2010 by Depositphotos / Stephen VanHorn.

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Trans fats: • Raise LDL (bad cholesterol) levels. • Reduce LDL particle size (smaller is worse). • Lower HDL (good cholesterol) levels. • Raise triglycerides (blood fat) levels. • Increases biomarkers of cellular inflammation. • May impair the action of endothelial cells lining artery walls, making arteries stiffer. • May impair the action of proteins that help break down blood clots. Trans fats do numerous things to alter the body’s chemistry so that it becomes more susceptible to clogged arteries. These fats may inhibit the dissolution of blood clots, increasing the likelihood of a cardiovascular event in people with narrowed arteries. The authors of the New England Journal of Medicine review article referenced above offer the following advice about trans fats: Complete or near avoidance of industrially produced trans fats— consumption of less than 0.5% of the total energy intake—may be necessary to avoid adverse effects and would be prudent to minimize health risks. For a 2,000-calorie diet, 0.5 percent equals ten calories, which is approximately the amount found in one gram of trans fat. My advice is to avoid all industrially produced trans fats. To do this, you must read your nutrition labels. Any product advertising any amount of trans fats in a serving size should be avoided, since serving sizes are typically smaller than the average person consumes. Therefore, trans fat consumption will probably be greater than the ten calories recommended above. Also, because food manufacturers are allowed to “round down” if there is less than 0.5 gram per serving (they can—and probably will—claim 0)9, you have to consult the product’s label ingredient list for the words “partially hydrogenated …” and “modified.” These adjectives indicate a chemical process that creates trans fats. Avoid foods with partially hydrogenated oil and modified fats as ingredients, regardless of the trans fat claim on the nutrition label.

9  http://www.fns.usda.gov/fdd/facts/nutrition/TransFatFactSheet.pdf, June 3, 2013.

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Fat Review Fat is one of the three macronutrients required by the human body to function normally. It should be a part of your regular diet. Some fat in every meal helps to control appetite. Choose unsaturated fats instead of saturated when possible. Consuming more omega-3 fat may be healthy for you. Avoiding trans fat is healthy for you. Some fat is good for you.

A Final Word about Diet and Nutrition If you are trying to control your weight, one of the most important things you must consider is how MUCH you are eating. All diets that constrain total calories below about 1,500 calories a day will result in weight loss for most adults when combined with an exercise program. These strategies may help you lower daily calorie intake: 1. Use a smaller plate to serve food, making your portion size smaller. A portion-control plate may be an effective tool. 2. Put your fork or spoon down on the table after two or three bites. This will increase the amount of time it takes you to eat your meal, which gives the stretch receptors in your stomach time to react to the food you are eating. You may get full before you complete your meal. Drinking a low- or zerocalorie beverage may also help fill your stomach. 3. Incorporate a small amount of fat in your meal. For vegetable-based meals, use something like olive oil when cooking or as a salad dressing. 4. Begin keeping a food journal, recording all you eat and drink during the day. Analyze the data by using a smart phone app or a website like myplate. gov to see how many calories you are eating, and which foods are providing them in larger quantities. Can you lower the intake of high-calorie foods? 5. Consider taking a multivitamin to ensure you are properly nourished. If you are cutting calories, the mantra of nutrient density becomes very important. You must eat foods rife with vitamins and minerals to ensure your body gets all the essential nutrients it needs. Fruits and vegetables are nutrient-dense foods. All healthy diets will incorporate these foods.

vi. rEducing rEcidivism Or How I made my parole offIcer Happy Within the past decade, exercise studies that have used health coaches and incentives (goals and rewards) have achieved adherence rates as high as 80 percent for programs that have lasted as long as a year. This is much better than the typical 50 percent or lower adherence rate referred to in Chapter 1. Setting behavior targets, tracking behavior, and assessing success (or failure) are critical for successful behavior change. This section of appendices discusses how to perform these critical tasks.

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Appendix

I

1

Goal Setting

n this appendix, we review the keys to effective goal setting. Goals, and their allies, objectives, are very effective at helping people change their behavior.

Goal versus Objective I frequently see these two terms used interchangeably. This suggests they are very similar concepts. In the context of our discussion, a goal will be considered a longer-term, higher-level desire. Goals usually take a long time to achieve and require a lot of effort. Objectives are shorter-term, specific things we use as stepping stones to get us closer to our goals.

SMART Goals and Objectives SMART is an acronym that refers to traits common to well-crafted goals and objectives. Since people often begin an exercise program because they want to lose weight, let’s explore SMART, using weight loss as our desired outcome. Here is an example of an un-SMART goal: I want to lose weight before my friend’s wedding. Here’s an example of a SMARTer goal: “I want to start walking every evening so I can lose 20 pounds of fat weight in 15 weeks as measured by my bathroom scale.”

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Specific “ … 25 pounds of fat weight … ” is SMARTer because it specifies exactly how much and what type of weight I want to lose.

Measurable “20 pounds” and “bathroom scale” are SMART pieces of information about how I am going to measure change. You must assess progress toward your goals in order for them to be effective. Measurement is a requirement.

Actionable “ … walking every evening … ” Goals must be active, not passive, or they will not provide much motivation.

Realistic Twenty pounds in 15 weeks is a realistic weight loss goal. Following a healthy program of diet and exercise, you should lose one to two pounds a week.

Time-Bound “Fifteen weeks” provides crucial information about when and how often you will assess progress toward your goal. Fifteen weeks is a relatively long time, so a goal like this should include shorter-term objectives such as:

Short-term objectives allow for behavior correction when you are falling behind schedule and provide positive reinforcement when you are successful.

• lose four pounds in two weeks • lose six pounds in four weeks • lose eight pounds in six weeks Shorter-term objectives are critical for good goals because they give important information about your progress. This information can support your actions by showing you are on track and, perhaps more importantly, telling you when you need to change course.

appendix

2

fitness testing

t

he four components of physical fitness are body composition, cardiorespiratory endurance, muscle strength and endurance, and flexibility. This appendix reviews several fitness tests that can be done without specialized equipment. Improving your score on one or more of these tests would be a way to demonstrate your exercise routine is effective. You should do these tests within the first week or two of your new exercise program, and then evaluate your progress according to your SMART long- and short-term goals and objectives.

A. Body Composition Body Mass Index The simplest way to track weight loss is to use an accurate scale. Body mass index (BMI) is a common, though controversial (see Chapter 4), way to frame weight-loss goals. Medical guidelines for body mass index are:

Because BMI does not take into account muscle mass, I do not recommend using it.

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BMI < 18.5 = underweight (unhealthy) 18.5 ≤ BMI < 25 = normal weight (healthy) 25 ≤ BMI < 30 = overweight (unhealthy?) BMI ≥ 30 = obese (unhealthy). To compute your BMI, you need your height (in inches) and your weight. Then use an online calculator like the one at the National Heart, Lung, and Blood Institutes website: http://www.nhlbi.nih.gov/guidelines/obesity/ BMI/bmicalc.htm

Copyright © 2012 by JKS, (CC BY-SA 3.0) at: http://commons.wikimedia.org/ wiki/File:Body_Fat_Caliper.png.

fitnEss tEsting | 95

Body Fat Percentage

Source: USMC. Copyright in the Public Domain.

One of the most exact ways to measure the effect of exercise on body weight is to calculate body fat percentage. When we exercise to lose weight, we want the weight loss to come from fat reserves. Unfortunately, the body may also consume some muscle tissue. Water loss is another common outcome of exercise. Both muscle catabolism and dehydration will cause the numbers on a scale to go down. In order get a more accurate reflection of the healthy changes our bodies undergo with exercise, we should look at body fat percentage. However, this does require more specialized equipment like a hand-held bioelectric impedance device that uses electricity to determine fat content, or skinfold calipers that measure fat under the skin to estimate overall body fat. A healthy body fat percentage depends on your sex. For women, essential body fat is thought to be around ten percent, meaning that if females have less than that, their bodies (specifically their reproductive functions) will be compromised. For men, body fat Body Fat goal: can be somewhere around three percent without Women—25 percent negatively affecting health. Men—18 percent Generally speaking, when counseling clients, I recommend that women strive for 25 percent body fat, while men should be around 18 percent. This is a personal recommendation based on the fact that these numbers are in the “average” category. Having a little more fat is not necessarily unhealthy.

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B. Cardiorespiratory Endurance VO2 max The gold standard for measuring cardiorespiratory fitness is assessing how much oxygen the body consumes during maximal effort (i.e., running as hard as possible on a treadmill, known as VO2 max testing). To do this accurately, You should warm up for three to five you have to be in a laboratory with minutes before testing. a gas analyzer strapped to your face. There are a couple of field tests that can approximate your VO2 max. You will have to do a little basic math to arrive at your score.

Queens College Step Test (Total test time: five minutes) Equipment: Stopwatch, metronome (88 BPM women, 96 BPM men), bench (set to 16.25”) This test requires you to step up and down off a bench for three minutes to a specific tempo (see above). When the three minutes are up, stop stepping and immediately locate your pulse at your radial artery. It’s important to do this as quickly as possible to get an accurate reflection of your working heart rate. Count your heart rate for 15 seconds. This is your recovery heart rate (RHR). • Recovery Heart Rate (RHR):____________ Estimate your VO2max (mL/kg per min) by plugging RHR into one of these equations. Men: 111.33 – (0.42 × RHR) = ________________ (0.1847 × RHR) =____________

Women: 65.81 –

Rockport 1-Mile Walk (Total test time: varies) Equipment: Stopwatch, one-mile course During this test, you will be walking as quickly as possible for one mile. Walking means the heel of the foot must strike the ground first. Do not run. You are trying to complete the mile in the shortest amount of time possible. When you finish the mile, stop the watch and immediately locate your pulse. Take a 15-second heart rate measurement.

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Time to complete mile (minutes):____________ 15-sec heart rate × 4 (beats per minute): _________ Weight in kilograms (1 kg = 2.2 pounds):_____________ Age:_______________ Sex (female = 0, male = 1):______________ VO2max = 132.853 – (0.0769 × weight) – (0.3877 × age) + (6.315 × sex) – (3.2649 × time) – (0.1565 × HR) VO2max:________________

C. Muscle Strength and Endurance Two common tests that can be done without special equipment are the curl-up and push-up tests.

Push-Up Test To do the push-up test, you can use either your toes or knees as the pivot point. Hands are placed shoulder width apart with your spine in its neutral position (no sagging). Your chin should be off the chest, with eyes looking directly at the floor. Bend your elbows until your chin touches the floor, or if you are doing the test with a partner, have her put her fist pinkie finger–side down on the floor and lower yourself until your chest touches it. Return to the up position with elbows fully extended. • Stomach should not touch mat • Only brief rest allowed in up position • Exhale when pushing away from the floor The test ends when you are unable to: • Fully extend the elbows • Bring chin or chest all the way to the floor/fist • Keep the stomach off the floor • Continue push-ups without taking a long rest at top Number of push-ups completed with good form:________________

Males Age 20–29 Balke Treadmill % (time) 99 95 90 85 80 75 70 65 60 55 50 45 40 35 30 25 20 15 10  5  1

32:00 28:31 27:00 26:00 25:00 23:40 23:00 22:00 21:15 21:00 20:00 19:26 18:50 18:00 17:30 17:00 16:00 15:00 14:00 12:00  8:00

Total n=15,764

Max V02 (ml/kg/ min) 61.2 56.2 54.0 52.5 51.1 49.2 48.2 46.8 45.7 45.3 43.9 43.1 42.2 41.0 40.3 39.5 38.1 36.7 35.2 32.3 26:6 n = 2,606

Age 30–39 12 Min 1.5 Mile Run Run (miles) (time) 2.02 1.88 1.81 1.77 1.73 1.68 1.65 1.61 1.58 1.57 1.53 1.51 1.49 1.45 1.43 1.41 1.37 1.33 1.29 1.21 1.05

 8:22  9:10  9:34  9:52 10:08 10:34 10:49 11:09 11:27 11:34 11:58 12:11 12:29 12:53 13:08 13:25 13:58 14:33 15:14 16:46 20:55

Balke Treadmill (time)

Max V02 (ml/kg/ min)

30:00 27:11 26:00 24:45 23:30 22:30 22:00 21:00 20:20 20:00 19:00 18:15 18:00 17:00 16:15 15:40 15:00 14:00 13:00 11:10  8:00 n = 13,158

58.3 54.3 52.5 50.7 47.5 47.5 46.8 45.3 44.4 43.9 42.4 41.4 41.0 39.5 38.5 37.6 36.7 35.2 33.8 31.1 26.6

12 Min Run (miles)

1.5 Mile Run (time)

1.94 1.82 1.77 1.72 1.67 1.63 1.61 1.57 1.55 1.53 1:49 1.46 1.45 1.41 1.38 1.36 1.33 1.29 1.25 1.18 1.05

 8:49  9:31  9:52 10:14 10:38 10:59 11.09 11:34 11:49 11:58 12:25 12:44 12:53 13:25 13:48 14:10 14:33 15:14 15:56 17:30 20:55

S

E

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p

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Percentile Values For Maximal Aerobic Power (Males)

MALES

%

29:06 57.0 26:16 52.9 25:00 51.1 23:14 48.5 22:00 46.8 21:02 45.4 20:15 44.2 20:00 43.9 19:00 42.4 18:02 41.0 17:34 40.4 17:00 39.5 16:12 38.4 15:38 37.6 15:00 36.7 14:20 35.7 13:35 34.6 12:45 33.4 11:40 31.8 10:00 29.4  7:00 25.1 n = 16,534 Total n = 25,636

1.90 1.79 1.73 1.66 1.61 1.58 1.54 1.53 1.49 1.45 1.44 1.41 1.38 1.36 1.33 1.31 1.28 1.24 1.20 1.13 1.01

1.5 Mile Balke Treadmill Run (time) (time)  9:02  9:47 10:09 10:44 11:09 11:32 11:52 11:58 12:25 12:53 13:05 13:25 13:50 14:10 14:33 15:00 15:32 16:09 17:04 18:39 22.22

AGE 50–59 Max V02 12 Min (ml/kg/ Run min) (miles)

27:15 24:00 22:00 20:31 19:35 18:32 18:00 17:00 16:10 16:00 15:02 14:56 14:00 13:05 12:38 12:00 11:10 10:15  9:15  7:30  4:20

54.3 49.7 46.8 44.6 43.3 41.8 41.0 39.5 38.3 38.1 36.7 36.6 35.2 33.9 33.2 32.3 31.1 29.8 28.4 25.8 21.3 n = 9,102

1.82 1.69 1.61 1.55 1.52 1.47 1.45 1.41 1.38 1.37 1.33 1.33 1.29 1.26 1.24 1.21 1.18 1.14 1.10 1.03 0.90

1.S Mile Run (time)  9:31 10:27 11:09 11:45 12:08 12:37 12:53 13:25 13.53 13:58 14:33 14:35 15:14 15:53 16:16 16:46 17:30 18:22 19:24 21:40 27:08

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P

VP

Fitness Testing | 99

99 95 90 85 80 75 70 65 60 55 50 45 40 35 30 25 20 15 10  5  1

AGE 40–49 Balke Max V02 12 Min Treadmill (ml/kg/ Run (time) min) (miles)

% 99 95 90 85 80 75 70 65 60 55 50 45 40 35 30 25 20 15 10  5  1

AGE 60–69 Balke Max V02 12 Min Treadmill (ml/kg/ Run (time) min) (miles)

25:02 51.1 21:33 46.1 19:30 43.2 18:00 41.0 17:00 39.5 16:00 38.1 15:00 36.7 14:30 35.9 13:51 35.0 13:04 33.9 12:30 33.1 12:00 32.3 11:21 31.4 10:49 30.6 10:00 29.4  9:29 28.7 27.4  8:37  7:33 25.9  6:20 24.1  4:55 22.1  2:29 18.6 n = 2,682 Total n = 3,149

1.74 1.60 1.51 1.45 1.41 1.37 1.33 1.31 1.29 1.26 1.23 1.21 1.19 1.17 1.13 1.11 1.08 1.03 0.99 0.93 0.83

1.5 Mile Balke Treadmill Run (time) (time) 10:09 11:20 12:10 12:53 13:25 13:58 14:33 14:55 15:20 15:53 16:19 16:46 17:19 17:49 18:39 19:10 20:13 21:34 23:27 25:58 31:59

AGE 70–79 Max V02 12 Min (ml/kg/ Run min) (miles)

24:00 19:00 17:00 16:00 14:34 13:25 12:27 12:00 11:00 10:30 10:00  9:20  9:00  8:21  7:38  7:00  6:00  5:00  4:00  3:00  2:00

49.7 42.4 39.5 38.1 36.0 34.4 33.0 32.3 30.9 30.2 29.4 28.5 28.0 27.1 26.0 25.1 23.7 22.2 20.8 19.3 17.9

1.69 1.49 1.41 1.37 1.32 1.27 1.23 1.21 1.17 1.15 1.13 1.11 1.09 1.07 1.04 1.01 0.97 0.93 0.89 0.85 0.81

1.S Mile Run (time) 10:37 12:25 13:25 13:57 14:52 15:38 16:22 16:46 17:37 18:05 18:39 19:19 19:43 20:28 21:28 22:22 23:55 25:49 27:55 30:34 33:30

S

E

G

F

P

VP

n = 467

S, superior; E, excellent; G, good; F, fair; P, poor; VP, very poor. From American College of Sports Medicine. ACSM’s Guidelines for Exercise Testing and Prescription, 8th ed. Philadelphia (PA): Wolters Kluwer Health Ltd: 2009, 84–86 pp.

100  |  Why Exercise is Important

MALES

Percentile Values For Maximal Aerobic Power (FEMales) FEMales Age 20–29 Balke Treadmill % (time) 27:43 24:24 22:30 21:00 20:04 19:42 18:06 17:45 17:00 16:00 15:30 15:00 14:11 13:36 13:00 12:04 11:30 10:42 10:00  7:54  5:14

Total n = 5,744

55.0 50.2 47.5 45.3 44.0 43.4 41.1 40.6 39.5 38.1 37.4 36.7 35.5 34.6 33.8 32.4 31.6 30.5 29.4 26.4 22.6 n = 1,350

12 Min 1.5 Mile Run Run (miles) (time) 1.84 1.71 1.63 1.57 1.54 1.52 1.46 1.44 1.41 1.37 1.35 1.33 1.30 1.27 1.25 1.22 1.19 1.16 1.13 1.05 0.94

 9:23 10:20 10:59 11:34 11:56 12:07 12:51 13:01 13:25 13:58 14:15 14:33 15:05 15:32 15:56 16:43 17:11 17:53 18:39 21:05 25:17

Balke Treadmill (time)

Max V02 (ml/kg/ min)

12 Min Run (miles)

1.5 Mile Run (time)

26:00 22:06 20:34 19:03 18:00 17:30 16:30 16:00 15:02 15:00 14:00 13:30 13:00 12:03 12:00 11:00 10:20  9:39  8:36  7:16  5:20

52.5 46.9 44.7 42.5 41.0 40.3 38.8 38.1 36.7 36.7 35.2 34.5 33.8 32.4 32.3 30.9 29.9 28.9 27.4 25.5 22.7

1.77 1.62 1.56 1.50 1.45 1.43 1.39 1.37 1.33 1.33 1.29 1.27 1.25 1.21 1.21 1.17 1.15 1.12 1.08 1.02 0.94

 9.25 11:08 11:43 12:23 12:53 13:08 13:41 13.58 14:33 14:33 15:14 15:35 15:56 16:43 16:46 17:38 18:18 19:01 20:13 21:57 25:10

n = 4,394

S

E

G

F

p

VP

Fitness Testing | 101

99 95 90 85 80 75 70 65 60 55 50 45 40 35 30 25 20 15 10  5  1

Max V02 (ml/kg/ min)

Age 30–39

% 99 95 90 85 80 75 70 65 60 55 50 45 40 35 30 25 20 15 10  5  1

AGE 40–49 Balke Max V02 12 Min Treadmill (ml/kg/ Run (time) min) (miles)

25:00 51.1 20:56 45.2 19:00 42.4 17:20 40.0 16:34 38.9 16:00 38.1 15:00 36.7 14:14 35.6 13:56 35.1 13:02 33.8 12:39 33.3 12:00 32.3 11:30 31.6 11:00 30.9 10:10 29.7 10:00 29.4  9:00 28.0  8:07 26.7  7:21 25.6  6:17 24.1  4:00 20.8 n = 4,834 Total n = 7,937

1.74 1.57 1.49 1.43 1.40 1.37 1.33 1.30 1.29 1.25 1.24 1.21 1.19 1.17 1.14 1.13 1.09 1.06 1.03 0.98 0.89

1.5 Mile Balke Treadmill Run (time) (time) 10:09 11:35 12:25 13:14 13:38 13:58 14:33 15:03 15:17 15:56 16:13 16:46 17:11 17:38 18:26 18:39 19:43 20:49 21:52 23:27 27:55

AGE 50–59 Max V02 12 Min (ml/kg/ Run min) (miles)

21:00 17:16 16:00 15:00 14:00 13:15 12:23 12:00 11:23 11:00 10:30 10:00  9:30  9:00  8:30  8:00  7:15  6:40  6:00  4:48  3:00

45.3 39.9 38.1 36.7 35.2 34.1 32.9 32.3 31.4 30.9 30.2 29.4 28.7 28.0 27.3 26.6 25.5 24.6 23.7 21.9 19.3 n = 3,103

1.57 1.42 1.37 1.33 1.29 1.26 1.23 1.21 1.19 1.17 1.15 1.13 1.11 1.09 1.07 1.05 1.02 1.00 0.97 0.92 0.85

1.S Mile Run (time) 11:34 13:16 13:58 14:33 15:14 15:47 16:26 16:46 17:19 17:38 18:05 18:39 19:10 19:43 20:17 20:55 21:57 22:53 23:55 26:15 30:34

S

E

G

F

P

VP

102  |  Why Exercise is Important

FEMALES

FEMALES

%

19:00 42.4 15:09 36.9 13:33 34.6 12:28 33.0 12:00 32.3 11:04 31.0 10:30 30.2 10:00 29.4 29.1  9:44 28.3  9:11  8:40 27.5 26.9  8:15  8:00 26.6  7:14 25.4  6:52 24.9  6:21 24.2 23.7  6:00  5:25 22.8  4:40 21.7  3:30 20.1  2:10 18.1 n = 1,088 Total n = 1,297

1.49 1.34 1.27 1.23 1.21 1.18 1.15 1.13 1.12 1.10 1.08 1.06 1.05 1.02 1.01 0.99 0.97 0.95 0.92 0.87 0.82

1.5 Mile Balke Treadmill Run (time) (time) 12:25 14:28 15:32 16:22 16:46 17:34 18:05 18:39 18:52 19:29 20:08 20:38 20:55 22:03 22:34 23:20 23:55 25:02 26:32 29:06 33:05

AGE 70–79 Max V02 12 Min (ml/kg/ Run min) (miles)

19:00 15:00 12:50 11:46 10:30 10:00  9:15  8:43  8:00  7:37  7:00  6:39  6:05  5:28  5:00  4:45  4:16  4:00  3:00  2:00  1:00

42.4 36.7 33.5 32.0 30.2 29.4 28.4 27.6 26.6 26.0 25.1 24.6 23.8 22.9 22.2 21.9 21.2 20.8 19.3 17.9 16.4

1.49 1.33 1.25 1.20 1.15 1.13 1.10 1.08 1.05 1.04 1.01 1.00 0.98 0.95 0.93 0.92 0.90 0.89 0.85 0.81 0.77

1.S Mile Run (time) 12:25 14:33 16:06 16:57 18:05 18:39 19:24 20:02 20:54 21:45 22:22 22:54 23:47 24:54 25:49 26:15 27:17 27:55 30:34 33:32 37.26

S

E

G

F

P

VP

n = 209

S, superior; E, excellent; G, good; F, fair; P, poor; VP, very poor. From American College of Sports Medicine. ACSM’s Guidelines for Exercise Testing and Prescription, 8th ed. Philadelphia (PA): Wolters Kluwer Health Ltd: 2009, 87–89 pp.

Fitness Testing | 103

99 95 90 85 80 75 70 65 60 55 50 45 40 35 30 25 20 15 10  5  1

AGE 60–69 Balke Max V02 12 Min Treadmill (ml/kg/ Run (time) min) (miles)

104  |  Why Exercise is Important

Curl-Up Test Equipment: Metronome, tape To prepare for this test, you will put two strips of tape on the floor, ten centimeters apart. Lie on the floor with the tip of your longest finger resting on the edge of the first piece of tape. Put the soles of your feet flat on the ground (knees in the air). Set the metronome to 60 beats per minute. The test begins when you start contracting your abdominal muscles, curling up while sliding the fingers along the floor until they reach the second piece of tape. Move up with the first beat. Return to the floor, making sure to bring the head all the way back down, with the next beat. Repeat until you are unable to maintain the tempo or cannot move all the way up to the second piece of tape.

D. Flexibility Because the flexibility of the hamstrings (muscles of the back of the thigh) may be related to low back function, here is an easy flexibility test you can do to see if you may want to improve this. Test one leg at a time with this test. You may want to have another person help with this test.

Fitness Categories For Push-Up age CATEGORY

20–29

30–39

40–49

50–59

60–69

SEX

M

F

M

F

M

F

M

F

M

F

Excellent Very good

36

30

30

27

25

24

21

21

18

17

35

29

29

26

24

23

20

20

17

16

29

21

22

20

17

15

13

11

11

12

28

20

21

19

16

14

12

10

10

11

22

15

17

13

13

11

10

 7

 8

 5

21

14

16

12

12

10

 9

 6

 7

 4

17

10

12

 8

10

 5

 7

 2

 5

 2

Needs improvement 16

 9

11

 7

 9

 4

 6

 1

 4

 1

Good

Fair

Source: Canadian Physical Activity, Fitness & Lifestyle Approach: CSEP-Health & Fitness Program’s Health-Related Appraisal & Counseling Strategy, 3e. 2003, 7–47 and 7–48 pp.

Fitness Testing | 105

Straight-Leg Raise Lie on the floor with one foot flat on the ground and the other leg straight (knee fully extended). Using your arms, lift the straight leg up in the air as high as possible, bringing the knee toward your nose. A passing score is being able to get your leg perpendicular to the ground with the ankle flexed (sole of the foot facing the ceiling). • Knee must stay straight

Fitness Categories For Partial Curl-Up age CATEGORY

20–29

30–39

40–49

50–59

60–69

SEX

M

F

M

F

M

F

M

F

M

F

Excellent Very good

25

25

25

25

25

25

25

25

25

25

24

24

24

24

24

24

24

24

24

24

21

18

18

19

18

19

17

19

16

17

20

17

17

18

17

18

16

18

15

16

16

14

15

10

13

11

11

10

11

 8

15

13

14

 9

12

10

10

 9

10

 7

11

 5

11

 6

 6

 4

 8

 6

 6

 3

Needs improvement 10

 4

10

 5

 5

 3

 7

 5

 5

 2

Good

Fair

Source: Canadian Physical Activity, Fitness & Lifestyle Approach: CSEP-Health & Fitness Program’s Health-Related Appraisal & Counseling Strategy, 3e. 2003, 7–47 and 7–48 pp.

106  |  Why Exercise is Important

Copyright © 2010 by Depositphotos / rognar. Reprinted with permission.

Appendix

3

Biometric Goals and Objectives

T

his appendix provides a brief description of and discussion about common biological measurements that are used by your doctor to assess your health. Exercise can improve these scores. Measuring changes in these areas can demonstrate that your exercise program is effective.

Blood Pressure High blood pressure increases your risk for cardiovascular disease. An average, healthy resting blood pressure score is 120/80. These two numbers reflect a range of pressure values inside your arteries and veins while your heart is beating. The first number, 120, is called systolic blood pressure (SBP). When your heart contracts, the blood inside is forced out into the arteries, which makes your blood pressure go up. Your highest pressure point occurs when the heart is exerting its maximal force against the blood. When the heart relaxes, blood flows from the body into the heart, reducing blood pressure. This lowest pressure point, 80, is called diastolic blood pressure (DBP). When your nurse is reciting your blood pressure score, he is essentially saying, “When your heart beats, your pressure goes up to 120, and when it relaxes, the pressure drops down to 80.” Blood pressure is measured by millimeters (mm) of mercury (Hg). This is the unit of pressure. High blood pressure, or hypertension, occurs when SBP is 140 or higher and/or DBP is 90 or more. At these pressure scores, your arteries are under so much stress that there is an increased risk they will rupture. Hypertension 107

108 | Why ExErcisE is important

Categories for Blood Pressure Levels in Adults (Ages 18 Years and Older) BlOOd Pressure leVel mmHg) Category

systolic

 

diastolic

Normal

< 120

and

< 80

Prehypertension

120–139

or

80–89

Stage 1 Hypertension

140–159

or

90–99

Stage 2 Hypertension

≥ 160

or

≥ 100

High Blood Pressure

also puts a lot of stress on internal organs like your kidneys, increasing their failure rate. Regular cardiorespiratory exercise like walking and swimming helps control high blood pressure (see Chapter 3 and 7). If your blood pressure is higher than 120/80, you should try to lower it. You can purchase a blood pressure monitor (this may be Sit quietly for five minutes before getting your blood pressure taken to get a reimbursed if you have health inmore accurate reading of your resting surance) or take advantage of free state. screenings provided at local drug stores, health fairs, or health clinics. Some doctors believe a blood pressure of 100/70 or lower is ideal. Taken from http://www.nhlbi.nih.gov/hbp/detect/categ.htm#normal

Cholesterol High cholesterol increases your risk for cardiovascular disease. Your total cholesterol score should be less than 200 milligrams per decaliter (mg/dL) of blood. Lower is better. Your HDL and LDL scores are also important. You should fast (no eating or drinking) HDL (the good stuff) should be for eight hours before giving a blood above 40 mg/dL, and LDL (the sample for a cholesterol test. bad stuff) should be less than 130 mg/dL. An ideal HDL score is 60 mg/dL or more. Ideal LDL is less than 100 mg/dL.

Biometric Goals and Objectives  |  109

Cholesterol Cholesterol If you …

then …

Your risk for cardiovascular disease.

200 mg/dL < Your total cholesterol score. The lower the better! 40 mg/dL < Your HDL (good cholesterol) score. Ideally it’s 60 mg/dL or more. 130 mg/dL > Your LDL (bad cholesterol) score. Ideally it’s less than 100 mg/dL.

Cardiorespiratory exercise can help you control your cholesterol, keeping the total cholesterol score down while raising your HDL levels. Your total cholesterol score is best determined by having a lab analyze a blood sample. This is typically performed as part of an annual physical (you should arrange to get the lab paperwork ahead of time so your doctor has the report during your meeting).

Glucose High glucose (blood sugar) is an indication that you are developing, or already have, diabetes. Under normal, healthy conditions, your body maintains

Glucose Levels Glucose If you …

then …

Your body’s responsiveness to insulin.

85 mg/dL ± 5 points = Healthy Blood Sugar Level For College-Age Students 101–124 mg/dL = Insulin Resistant 125+ mg/dL = Diabetes

110 | Why ExErcisE is important

blood sugar in a very narrow range. You MUST fast (no eating or drinking) In my experience with college-age for at least eight hours before giving a students, that number is within five blood sample for this test, or the results points of 85 milligrams per decaliter will be meaningless. (mg/dL) of blood. As the number rises, it indicates that your body is becoming less responsive to insulin, the hormone that helps sugar enter cells. When your score passes 100, you become defined as having insulin resistance. Without meaningful lifestyle change (see Chapter 4), the score will probably continue to increase. Once it surpasses 125, you have diabetes. Your glucose score is best determined by having a lab analyze a blood sample. This is typically performed as part of an annual physical (you should arrange to get the lab paperwork ahead of time so your doctor has the report during your meeting).