The Best Anti-Aging Workout You Can Do

Workouts make you younger. It all boils down to the fact that exercise increases your mitochondria, the power centers of every cell in your body. The more plentiful and efficient your mitochondria are, the better each cell works-whether that's a skin cell cranking out plumping collagen or a muscle cell laying down strength-building fibers-and the younger your body looks, feels, and operates. (Related: The #1 Workout That Keeps You Young, According to Research)

Doing all-out sprints for 30 seconds beat out steady cardio and longer, less-intense intervals (four minutes each at 90 percent effort) for boosting the power output of each unit of mitochondria, a new study at Victoria University in Australia found. Aim to incorporate HIIT three times a week. (There's a good chance it's possible to do too much HIIT.)

The key to maxing the mitochondria you have all over is cardio. In fact, endurance exercise can double the amount in your muscle, says Mark Tarnopolsky, M.D., Ph.D., a professor at McMaster University in Ontario. "By swabbing athletes' cheeks, we've found that they even have more mitochondria there," he says. Translation: If lowly cheek cells benefit, think of what your heart and skin reap. Indeed, Dr. Tarnopolsky's research found that twice-a-week cycling for 30 to 45 minutes (plus one weekly walk) helped skin increase its collagen-filled underlayer and refresh its outer layer more quickly-in effect, "youthening" within three months. (Related: Should You Be Exercising Your Face?)

"We've seen resistance training increase the amount of mitochondria by 30 percent in older adults who did three weight circuit workouts a week over four months," Dr. Tarnopolsky says. So is there one optimal strength training regimen to follow? A new review of studies in the journal Frontiers in Physiology that looked at resistance exercise and its effect on the amount of mitochondria in muscle suggests more research is needed to find the single best. In Dr. Tarnopolsky's study, subjects started with a weight that was half of the maximum they could lift in one rep and did sets of 10 to 12 reps, working their way up to three sets, then progressing to lifting heavier weights. (And this is just one of the many health and fitness benefits of lifting weights.)