Openmirrors.com Alex Hutchinson, Ph.D. WHICH COMES FIRST, CARDIO OR WEIGHTS? Fitness Myths, Training Truths, and Other Surprising Discoveries from the Science of Exercise For Lauren Openmirrors.com Contents Cover Title Page Introduction: What This Book Is (and Isn’t) Chapter 1 - Getting Started Chapter 2 - Fitness Gear Chapter 3 - The Physiology of Exercise Chapter 4 - Aerobic Exercise Chapter 5 - Strength and Power Chapter 6 - Flexibility and Core Strength Chapter 7 - Injuries and Recovery Chapter 8 - Exercise and Aging Chapter 9 - Weight Management Chapter 10 - Nutrition and Hydration Chapter 11 - Mind and Body Chapter 12 - The Competitive Edge Conclusions: From Lab to Gym Acknowledgments Index References About the Author Copyright About the Publisher Introduction: What This Book Is (and Isn’t) WHEN A RESEARCH INSTITUTE in La Jolla, California, issued a press release with the provocative title “Exercise in a Pill” in the summer of 2008, it wasn’t hard to predict the headlines that would be splashed across the next day’s newspapers. “Trying to reap the health benefits of exercise? Forget treadmills and spin classes,” the release proclaimed. “Researchers at the Salk Institute for Biological Studies may have found a way around the sweat and pain.” Feeding a drug called AICAR to a group of mice for four weeks allowed them to run 44 percent longer than drug-free mice, the new study found—without a single step of training. Stories like this are hard to resist. After all, who wouldn’t love a pain-free, effortless shortcut to fitness? That’s why we’re bombarded on a daily basis by similar promises in magazines, on television, over the Internet, and in our spam folders. There’s just one problem with these get-fit-quick schemes: they don’t work. Exercise, as medical physiologists Frank Booth and Matthew Laye of the University of Missouri pointed out in a critique of the Salk Institute study, affects almost every organ system in your body—circulatory, neural, endocrine, gastrointestinal, immune, kidney, skeletal muscle, bone, ligament, and so on. In fact, the only systems that don’t respond to exercise appear to be the senses and (surprisingly) the lungs. Unless a pill can somehow produce changes in all these systems simultaneously, it will never replace exercise. (Moreover, you don’t get healthy by having the capacity to run 44 percent farther—you can only burn calories and get the resulting benefits by actually doing it.) So let me begin with a full disclosure: this book does not contain any secret workouts or magic pills that will produce instant fitness. Instead, what follows is an up-to-date guide to what scientists know about exercise, health, and performance—and, just as importantly, what they don’t know. It’s an “evidence-based” guide: the answers it offers to common fitness questions aren’t based on conventional wisdom or gut feelings. Instead, they’re drawn from the more than 400 peer-reviewed journal articles listed in the reference section at the back, along with over 100 interviews with researchers around the world. That means that if scientists don’t yet have a definitive answer to a question, I haven’t just made one up. For example, the last few years have seen a surge of interest in running barefoot or in “minimalist” shoes, a practice that some people believe reduces the risk of injury compared with conventional running shoes. A few studies examining how running barefoot affects your joints have now been published, but the results so far have been ambiguous—so, in chapter 2, you can read about some of these studies and make up your own mind about whether the potential benefits outweigh the risks (and the funny looks). For someone who has been repeatedly injured trying to run in conventional shoes, the answer might be yes; for someone trying running for the first time, probably not. This is an important point: there’s no single “best” exercise program or technique that applies to everyone. You’ll have to take into account your background, current level of fitness, and goals in designing an appropriate workout regimen—not to mention more subtle considerations like the types of activity you enjoy. After all, the most effective program is the one you can stick with! No matter what type of exercise you choose, there are some basic concepts that govern the training process, in particular, the “Specific Adaptation to Imposed Demands” (SAID) principle: When the body is subjected to stresses and overloads of varying intensities, it will gradually adapt over time to overcome whatever demands are placed on it. That’s what every form of exercise boils down to. The stress could be lifting weights or pedaling a bicycle, and the adaptation is bigger muscle fibers, a stronger heart, and hundreds of other microscopic changes. The key is balancing the size of the stress: too small (lifting a half-pound weight, say), and your body won’t see any need to adapt; too large, and it won’t have a chance to adapt due to injury or exhaustion. Much of the research described in this book aims to help you find this delicate balance. Your body’s overall goal in making these adaptations is, simply put, to more efficiently convert the energy from your food into physical action. Every move you make is powered by the contraction of muscle fibers, and these contractions are fueled by a molecule called ATP (adenosine triphosphate) extracted from the carbohydrate, fat, and protein you’ve eaten. Your body has several different ways of converting nutrients to ATP. One supply is stored in a form called phosphocreatine, which can provide energy for short, intense bursts lasting up to about 10 seconds. A process called glycolysis offers another source of ATP that lasts about 45 seconds. Neither of these processes requires oxygen to create ATP, so they’re known as “anaerobic” (literally “without oxygen”) energy sources. For longer spurts of exercise, the tiny “power plants” in your cells called mitochondria can convert carbohydrate or fat to ATP, but the process requires oxygen—which is why sustained exercise is referred to as “aerobic.” As your body adapts to exercise, you’ll become more efficient at every step of this process. Your cells generate more mitochondria, enabling you to produce more ATP; you start burning a higher proportion of fat (a virtually unlimited form of stored energy) instead of carbohydrate; and the muscle fibers themselves produce more force with each contraction. In addition to these functional adaptations, your body will remodel its structure. Less fat and bigger muscles are the two most obvious changes, but other adjustments will be taking place under the surface. The constant tug of stronger muscles on your skeleton results in stronger bones; your heart literally grows bigger in order to pump more oxygen-rich blood to hard-working muscles; you develop a more extensive network of capillaries to distribute that blood; the nerves that carry commands from your brain to your muscles learn to do so more quickly and efficiently; and on and on. In some ways, though, the most important adaptations—and perhaps the most unexpected—are those that occur in the brain. This is a field of research that remains in its infancy, though it has been gathering momentum for the past few years. But what we do know for sure is that the increased flow of blood and growth factors to the brain during exercise has dramatic effects, boosting memory and learning, enhancing cognition, and warding off the effects of aging. And exercise also stimulates the release of powerful mood-altering chemicals like endorphins, so much so that some researchers argue that it can become a mild addiction. If that’s the case, it’s an outcome that I devoutly wish for everyone who reads this book. When, as a teenager, I started trying to run on a daily basis, it was a tremendous chore. It stayed that way for several years—until, during a layoff due to injury, I suddenly realized how much I missed it. These days, my workout is the highlight of my day, a chance to get outside, unwind, perhaps spend time with my wife or friends, or simply be alone with my thoughts. I don’t believe that researchers will ever succeed in producing “exercise in a pill”—but if they did, I wouldn’t be interested in taking it. I hope that, after reading this book and putting some of its ideas into practice, you’ll end up feeling the same way. Openmirrors.com Chapter 1 Getting Started IN 1960, PRESIDENT-ELECT JOHN F. KENNEDY wrote an article for Sports Illustrated called “The Soft American,” lamenting the declining role of physical activity in everyday life. “Today human activity, the labor of the human body, is rapidly being engineered out of working life,” he wrote. “By the 1970s, according to many economists, the man who works with his hands will be almost extinct.” That prediction didn’t quite pan out—but it’s certainly true that, for most of us, physical activity is now a choice rather than the necessity it was for our ancestors. Kennedy was concerned that Americans wouldn’t have the “vigor and determination” necessary to match the Soviet Union; today, we’ve realized that physical fitness is essential to the health of our bodies and minds. But the basic challenge remains the same: if you’ve just begun working out recently, or you’re about to head to the gym for the first time, you need to know what to expect. How hard to push, how long it will take to see results, how to make the most of your workout time, how to minimize the risks associated with starting an exercise program—these are the issues you should consider before getting started.