Most research on aging has been done on sedentary populations and so the results of most studies up to date have shown that "normal aging" causes muscle mass and strength to decline. But what if we looked at active older people? Would we still see the normal loss of muscle size and strength from age 40 to 70?
Researchers decided to do just this and look at an active population of men and women between 40 and 80 years old and measure their muscle mass and muscle strength. The results show that chronic exercise can have amazing benefits for older people and even completely stopping and possibly reversing muscle mass and strength normally associated with aging.
As they say, a photo is worth a thousand words:
"It is commonly believed that with aging comes an inevitable decline from vitality to frailty. This includes feeling weak and often the loss of independence. These declines may have more to do with lifestyle choices, including sedentary living and poor nutrition, than the absolute potential of musculo- skeletal aging. In this study, we sought to eliminate the con- founding variables of sedentary living and muscle disuse, and answer the question of what really happens to our muscles as we age if we are chronically active. This study and those discussed here show that we are capable of preserving both muscle mass and strength with lifelong physical activity."
https://physsportsmed.org/sites/default/files/rpsm.2011.09.1933_secure.pdf