"A study appearing this week in the online journal PLoS One looked at the effects of six months of strength training in 25 elderly volunteers aged 65 and older (average age: 70). The researchers took small biopsies of thigh-muscle cells from the seniors before and after the six-month period, then compared them with muscle cells from 26 young volunteers (average age: 22). "To be honest, we were expecting some indication that the exercise program improved strength," says biologist Simon Melov, director of genomics at the Buck Institute in Novato, Calif., and coauthor of the study. What the scientists didn't expect was what they actually found—that after six months of resistance training, there were dramatic changes at the genetic level. As Melov puts it, "The genetic fingerprint [of the elderly participants] was reversed to that of younger people—not entirely, but enough to say that their genetic profile was more like that of young people than old people."
So what are you waiting for? Don't delay!