By Amanda MacMillan
Updated: July 22, 2008
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tkGetty ImagesI'm 25, but on my morning jogs I'm often lapped by runners old enough to be my grandparents. This isn't humiliating—it's inspiring. And it turns out that fit seniors are doing more than remaining competitive on the jogging route: There's a slew of new research suggesting that they're saving their brainpower, fighting disease, and keeping themselves out of nursing homes.

Whether you're young and want to pass on this encouraging information, or approaching the senior age bracket yourself, here's a rundown of the benefits of exercise.

It can slash disability risk
Older adults can decrease their risk of disability by 41% by participating in a walking exercise program, according to a new University of Georgia study. Members of this exercise group met three times a week for four months, beginning with 10-minute walks and working up to 40 continuous minutes, plus warm-up and cool-down sessions that included balance and flexibility exercises. Motivated community members could lead similar groups across the country, the researchers note, at very little cost besides comfortable clothing and shoes.

It fosters independence
Simple resistance training can improve muscle strength, power, and functional performance in people over the age of 65, say Australian researchers who studied a twice-weekly, machine-based program that targeted major muscles of the upper and lower body. Lead researcher Tim Henwood, MD, says that while older people are encouraged to do basic aerobic exercises like walking, the benefits of strength training are as important—and perhaps more important—in the prevention of functional decline: "For this age group, these increases are what allows them to keep successfully climbing stairs and getting out of chairs, thereby allowing them to retain their independence."

It may stave off dementia
Among patients with mild Alzheimer's disease (age 60 and older), those with lower physical fitness levels (measured by cardiovascular tests on a treadmill) had four times more brain shrinkage when compared to normal adults than those who were more physically fit, according to a recent study from the University of Kansas School of Medicine. Decreased brain volume is tied to poorer cognitive function, says lead researcher Jeffrey M. Burns, MD, so staying active may translate into better cognitive performance and a slower progression of dementia.