further subdivided their samples by exercise habits. They found that after age 40, the men and women who exercised frequently had markedly thinner, healthier stratum corneums and thicker dermis layers in their skin. Their skin was much closer in composition to that of the 20- and 30-year-olds than to that of others of their age, even if they were past age 65.
But as the researchers realised, other factors, including diet, genes and lifestyles, might have influenced the differences in skin condition between the exercising and sedentary groups. It was impossible to know whether exercise by itself had affected peoples skin or been incidental to lucky genetics and healthy lives.
So the researchers next set a group of sedentary volunteers to exercising, after first obtaining skin samples from their buttocks. The volunteers were aged at 65 or older and, at the studys start, had normal skin for their age. They began a fairly straightforward endurance training program, working out twice a week by jogging or cycling at a moderately strenuous pace, equivalent to at least 65 percent of their maximum aerobic capacity for 30 minutes. This continued for three months. At the end of that time, the researchers again biopsied the volunteers skin.
But now the samples looked quite different, with outer and inner layers that looked very similar to those of 20- to 40-year-olds. I dont want to over-hype the results, but, really, it was pretty remarkable to see, said Dr Tarnopolsky, himself a middle-aged exerciser. Under a microscope, the volunteers skin looked like that of a much younger person, and all that they had done differently was exercise.
- GRETCHEN REYNOLDS