Almost any amount and type of physical activity may slow aging deep within our cells, a new study finds. And middle age may be a critical time to get the process rolling, at least by one common measure of cell aging.

Dating a cell’s age is tricky, because its biological and chronological ages rarely match. A cell could be relatively young in terms of how long it has existed but function slowly or erratically, as if elderly.

Today, many scientists have begun determining a cell’s biological age – meaning how well it functions and not how old it literally is – by measuring the length of its telomeres.

For those of us who don’t know every portion of our cells’ interiors, telomeres are tiny caps found on the end of DNA strands, like plastic aglets on shoelaces. They are believed to protect the DNA from damage during cell division and replication. As a cell ages, its telomeres naturally shorten and fray. But the process can be accelerated by obesity, smoking, insomnia, diabetes and other aspects of health and lifestyle.

A new study, which was published this month in Medicine & Science in Sports & Exercise, researchers from the University of Mississippi and University of California, San Francisco, decided to look broadly at the interactions of exercise and telomeres.

Their results show that risk declined more substantially if someone exercised more. People who reported two types of exercise per week were 24 percent less likely to have short telomeres; three types of exercise were 29 percent less likely; and those who had participated in all four types of activities were 59 percent less likely to have very short telomeres.

Interestingly, these associations were strongest among people between the ages of 40 and 65, the researchers found, suggesting that middle age may be a key time to begin or maintain an exercise program if you wish to keep telomeres from shrinking, says Paul Loprinzi, an assistant professor of health and exercise science at the University of Mississippi.

The message seems clear, Dr. Loprinzi says. “Exercise is good” for your cells, and “more exercise in greater variety” is likely to be even better.

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Source: the New York Times.