Exercise may well hold the key to the fountain of youth. Besides boosting longevity, getting fit is one of the most important steps older adults can take to maintain their mobility, independence and quality of life. Gone are the days when growing old gracefully meant slowing down and taking it easy. For the 77 million baby boomers born between 1946 and 1964 it means just the opposite. Inactivity, not aging is the culprit behind chronic conditions such as heart disease, obesity, and osteoporosis. The good news is, there is a lot you can do to delay or prevent them.

Use it or lose it

The physical benefits of exercise for older adults are the same as they are for twenty-somethings - increased muscle strength, flexibility, balance, and endurance. Strength is especially important. With age, muscle strength decreases about 10 percent every decade. These losses add up. Strong muscles are necessary for daily activities such as climbing stairs, carrying groceries and mowing the lawn, as well as for recreational activities like hiking or playing golf.

The weaker you are, the less you can do and the more dependent you become - a vicious cycle that often ends with admission to a nursing home. Muscle loss also leads to weight gain since muscle burns more calories than fat even at rest.

"We lose about a third of a pound of muscle each year after the age of 35 and gain at least that much fat," says Miriam Nelson, Director of the Center for Physical Activity and Nutrition at the School of Nutrition Science and Policy at Tufts University in Boston. "Your weight may stay the same or you may gain a bit, but inside your body, muscle is being replaced by fat. After 10 years you realize, 'Oh my gosh, I'm not nearly as strong as I used to be.'"

Strength training reverses that process. In a landmark 1990 study for example, ten nursing home residents aged 86 to 96, boosted their strength by a whopping average 175% after just eight weeks of resistance training. (They also had dramatic improvements in their balance and walking speed.) Strength training also benefits your bones. "Even if your diet is good, unless you stimulate the muscles you'll lose both muscle and bone. When you build muscle, you also build bone," says Nelson.

Besides boosting strength and helping with weight control, strength training improves cholesterol levels, relieves arthritic symptoms and helps prevent diseases such as diabetes and high blood pressure. It also lifts your spirits.

Even so, most older adults don't get the recommended amount of exercise every day. Surveys show that 30 percent of adults aged 45 to 64 engage in regular physical activity and only 32 percent of adults 65 an older do so. "Many people aren't aware of how profoundly physical activity can affect their health," says Lisa Oliphant, executive director of the President's Council on Physical Fitness and Sports. "As Americans age they have the false belief that exercise is only for young people and that becoming sedentary is a normal part of the aging process. "That's simply not true."

An Ounce of Prevention

Getting enough exercise isn't as hard as many people think. Thirty minutes a day is all it takes. Moreover, it doesn't have to be high intensity to provide health benefits. Even moderate activity such as gardening and walking can make a significant difference in health and well being. Unfortunately, our society isn't designed to encourage people to incorporate more activity into their normal routine. "We take the elevator instead of the stairs, drive instead of walk. Modern conveniences preclude activity in our daily lives," says Oliphant. Still, the effects of exercise add up. Several short 10 minutes bouts throughout the day can be equivalent to one 30-minute session. "You don't have to be a gym rat," says Oliphant. "It can be as simple as taking the dog for a walk after dinner. Any activity helps." Numerous studies have demonstrated the impact of regular physical activity on bone density, fat levels, blood sugar and a host of other age-related factors linked to decline and disease. What's more, it's never too late to start.

For baby boomers tied to the TV remote control however, getting off the couch and into shape holds more than the promise of better bones or lower cholesterol. Just ask John "The Penguin" Bingham. Before taking up running 10 years ago, the former freelance trombonist was a sedentary middle-aged smoker carrying around 80 extra pounds. (He got his nickname after seeing his reflection when he first started running). Today the 53-year-old marathoner and columnist for Runner's World magazine crisscrosses the country urging baby boomers to join the ranks of "adult onset athletes." "I've lived both lives," he says. "I know the things that exercise opens up to you. When you're active, you feel so much better about everything in your life."

That message is winning converts. In less than 10 years the first of the baby boom generation will turn 65. By 2030, one out of every five adults will be over 65 as boomers enter their seventies and eighties. As baby boomers age they are rejecting the notion that aging is synonymous with being frail and inactive.

"Ours is a generation that is redefining aging," says The Penguin. "We don't know what old is anymore." Aging baby boomers he says, should accept their limitations and go from there. "Decide to be an active person for the rest of your life and then do it for the pure joy of knowing that you're doing something for yourself," he says. "If you do that, you'll be content forever."