Photo by Jana Leon
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Living Longer: Exercise
By Susan Crandell, September & October 2006
Regular physical activity has been shown to reduce your risk of heart attack, stroke, Alzheimer’s, and some cancers. Now we’re finding it also may add years to your life. That’s powerful medicine indeed
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There are no guarantees in life and even fewer in death. But if you wish to prolong the former and delay the latter, scientists can now pretty much promise that regular exercise will help. "So many of what we thought were symptoms of aging are actually symptoms of disuse," says Pamela Peeke, M.D., a University of Maryland researcher and author of Body for Life for Women (Rodale, 2005). "This is a monster statement." It means that your health is not just a throw of the genetic dice but a factor that is largely under your control. "Our bodies are built for obsolescence after 50," Peeke says. "Up to 50 you can get away with not exercising; after that, you start paying the price."
The most dramatic declines due to aging are in muscle strength. "Unless you do resistance exercise—strength training with weights or elastic bands—you lose six pounds of muscle a decade," says Wayne Westcott, Ph.D., the highly respected fitness research director at the South Shore YMCA in Quincy, Massachusetts. That change in body composition not only saps our strength; it also lowers our metabolism and exposes us to greater risk of age-related disease. In fact, the loss of muscle (and accompanying increase in body fat) puts extra strain on the heart, alters sugar metabolism (increasing the risk for diabetes), and can tip the balance of healthy lipids in the blood, leading to heart attack and stroke.
 
Building muscle is much easier than you might think. Strength training just 20 minutes a day, two or three times a week, for 10 to 12 weeks can rebuild three pounds of muscle and increase your metabolism by 7 percent. Do you really need a boost in metabolism? Yes, if you want to feel more energetic, more alert, more vital and alive. Plus, the added muscle has a halo effect on many systems of the body, reducing blood pressure, improving your ability to use glucose from the blood by 25 percent, increasing bone mass by 1 to 3 percent, and improving gastrointestinal efficiency by 55 percent. "It's like going from a four-cylinder engine to a six," Westcott says.
If that's not enough to get your attention, consider this: a regular exercise program (30 minutes of physical activity at least three days a week) can reduce your risk of dying in the next eight years by 40 percent, improve brain function, cut your risk of Alzheimer's disease by up to 60 percent, and blunt the symptoms of depression. This is powerful medicine, given that 80 percent of the population over 65 suffers from at least one chronic condition, and half have two or more, according to a report from the Census Bureau and the National Institute on Aging.
What is it about physical activity that makes it such a panacea? As scientists learn more about how the aging process works, they're finding that exercise—both aerobic exercise and strength training—has a tremendous impact on every cell in the body, reducing inflammation, increasing blood flow, and even reversing the natural declines in oxygen efficiency and muscle mass that come with aging.
The most dramatic declines due to aging are in muscle strength.
Westcott points to a study his organization conducted at a nursing home in Orange City, Florida. Nineteen men and women with an average age of 89, most of whom used wheelchairs, did just ten minutes of strength training a week. "After 14 weeks almost everybody was out of their wheelchairs," Westcott says. "One woman moved back into independent living." The results were published in Mature Fitness.
Another inspiring study, published last spring in the Journal of the American College of Cardiology, reported that people in their 60s and 70s who walked or jogged, biked, and stretched for 90 minutes three times a week for six months increased their exercise efficiency—their ability to exercise harder without expending more energy—by a whopping 30 percent. But here's the shocker: a comparison group of people in their 20s and 30s showed an efficiency increase of just 2 percent. The results caught even study author Wayne C. Levy, M.D., an associate professor of cardiology at the University of Washington in Seattle, by surprise. "I hadn't anticipated that the older people would improve more than the group in their 20s and 30s," he says.
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The explanation, Levy believes, may involve improvement in the function of the mitochondria—spherical or rod-shaped structures in our cells that take glucose, protein, and fat from the food we eat and turn them into energy. In fact, scientists believe that most of the dramatic benefits we get from exercise can be traced to this improvement in the mitochondria. "Mitochondrial function naturally declines with age," explains Kevin Short, Ph.D., who studies mitochondria and exercise at the Mayo Clinic in Rochester, Minnesota. But exercise, he found, can reverse that decline.
When Short and his colleagues put 65 healthy nonexercisers ranging in age from 21 to 87 on a bicycle training program three days a week, they found that everyone's maximum aerobic capacity had increased by about 10 percent after four months. When they studied thigh-muscle samples, they found out why: the mitochondria were pumping out more adenosine triphosphate (ATP), the fuel muscles use to move.
Now, if mightier mitochondria aren't enough to get you on your exercise bike each morning, consider this: physical activity may also combat oxidative damage (see "Browning apples: oxidation at work" in 3 Key Aging Concepts). Abraham Aviv, M.D., director of the Center of Human Development and Aging at the University of Medicine and Dentistry of New Jersey, explains how it works: "During exercise there's a tremendous burst of oxidative agents that are injurious to tissue." But while you take in more oxygen while exercising, regular physical activity also slows your resting heart rate, making it more efficient. The net result? Exercise reduces the overall rate at which you create harmful free radicals.
Finally, to all these substantial benefits of exercise add one more: Professor Tim Spector, director of the TwinsUK registry at St. Thomas' Hospital in London, is conducting experiments to determine whether exercise slows down the rate at which our telomeres shrink. (Telomeres are DNA sequences, located on the ends of chromosomes, that shorten as we age—see "Telomeres: your body's biological clock" 3 Key Aging Concepts). Although the results have not yet been published, preliminary findings suggest that in exercising and sedentary twin pairs, the twin who exercises has much longer telomeres "even when you adjust for differences in weight and smoking," says Spector.
In short, the evidence is clear: daily physical activity can transform your life. And it's never too late to start. "I started strength-training my father when he was 82," recalls Westcott. "He's six feet tall, but he was emaciated by the stress of my mother's death and weighed only 124 pounds. In a year and a half, he added 24 pounds of muscle. At 97, he's stronger than people half his age."
Susan Crandell is the author of Thinking About Tomorrow: Reinventing Yourself at Midlife, to be published by Warner Books in January 2007.
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