Exercise already confers a host of benefits, from improved memory to better quality of sleep. Now researchers from McMaster University add another to the list. Working out roughly three times a week has been shown to keep skin younger and possibly reverse aging’s effects in people over 65.

The study, presented this month at the American Medical Society for Sports Medicine annual meeting, involved a crucial portion of the skin known as the stratum corneum. It’s the outermost layer of your skin — the one you scratch, sunburn, sweat through, and all around see. This also means it’s the layer that ages, perhaps not so gracefully, as we get older. It begins to sag, droop, wrinkle, color, splotch, and thicken. It also, because of the dying cells and diminishing elasticity, turns somewhat translucent.

All this is the opposite of what we vitality-seeking folks would like to happen, and thankfully researchers suggest there’s a way out. The alternative? Good old-fashioned exercise.

That answer isn’t glamorous, but then again, it seldom is. Exercise, the research team discovered, appeared to contribute to not only a preservation of subjects’ skin when they frequently exercised, but a reversal in “skin age” when they began exercising later in life.

To test their hypothesis, which they derived from prior research on mice, experimenters recruited 29 local men and women between the ages of 20 and 84. They separated each participant according to their usual level of exercise, with one group typically working out for three hours a week while the other group led a mostly sedentary lifestyle. Then they collected skin samples from subjects’ buttocks, theorizing this area would have minimal sun exposure.

Initial microscope tests confirmed what they already knew: older skin, irrespective of exercise level, showed thicker strata cornea and thinner dermis layers than younger subjects. When they stratified the sample based on age and exercise levels, the effect of exercise became clearer: Male participants in their forties had skin biopsies of 20- or 30-year-olds, and the effects persisted even past age 65.

But the team knew that their research had limits. Just by that data alone, they couldn’t tease out how much impact the sun, diet, and a person’s genetics contributed to younger-looking skin. So they conducted a follow-up experiment. This study included only those subjects 65 and older who, at the beginning of the first study, had normal skin for their age.

For three months, one group performed moderately intense exercise, either jogging or cycling, three times per week at 65 percent their aerobic limit. The other group did nothing. At the end of three months, the team found the outer and inner layers both resembled what scientists typically find in healthy 20- to 40-year-olds. “I don’t want to over-hype the results, but, really, it was pretty remarkable to see,” said Dr. Tarnopolsky, a professor of pediatrics at McMaster, to The New York Times.

The chief theory for how exercise wields this age-defying power involves a diverse group of proteins known as myokines. They’re secreted by muscle cells, but actually diffuse to far-off locations in the body. When researchers examined subjects’ biopsies, they found a specific type of myokine, called IL-15, was in greater concentrations, as much as 50 percent more, in those who exercised.

Tarnopolsky believes it may actually be a mix of substances within the body making exercise a protector of youth, and that no amount of “gravity-defying” pills or lotions can mimic their effects. “It is astonishing,” he said, “to consider all of the intricate ways in which exercise changes our bodies.”