It's already known that people who exercise regularly tend to live longer. A new study helps explain why. Researchers in Britain looked at the DNA of more than 2,000 twins. Specifically, they studied the length of the protective caps called telomeres, which decrease with age.
The doctors found that the telomeres of people who exercised 200 minutes or more per week were longer than those of people who exercised just 16 minutes or less per week. In fact, the telomere size difference suggested that the most active people were biologically 10 years younger than the least active.