Exercise benefits the body at any age, but a certain kind of exercise, new research finds, is particularly effective at counteracting the effects of aging on your muscles. It stimulates literally hundreds of genes that enhance the ability of muscle cells to convert nutrients into energy—an essential function that tends to decline with age. For younger people, this form of exercise is a good way to get fitter and healthier.

If you’re older, it’s a great way.

Background: There’s no question that exercise is key to aging gracefully—being fit and strong fights age-related risks for disease and disability. As we age, our muscle mass decreases—and our muscles become less efficient at turning oxygen and nutrients into energy. Exercise counters both trends. But little has been known about what kind of exercise is most effective at keeping older muscles younger.

Study: Researchers from Mayo Clinic in Rochester, Minnesota, enrolled healthy men and women in a study that looked at the effects of three different types of exercise. The first was resistance (strength) training. The second was high-intensity aerobic interval training (HIIT), during which the exerciser pushes all-out for a brief spurt and then recovers while exercising at a reduced pace, and then repeats the process. The third was a combination of moderate-intensity aerobic exercise plus less intense resistance training. The researchers evaluated various markers of health.

Unlike similar studies, however, this one was conducted on two groups of people in very different stages of life. The younger group was 18 to 30 years old…the older group, 65 to 80. Baseline laboratory tests and muscle biopsies were conducted at the beginning of the study and after it ended 12 weeks later.

Results: All three exercise types improved insulin sensitivity, a key way that exercise helps prevent diabetes. Both HIIT and combined aerobic/resistance training led to improvements in aerobic capacity. Resistance training increased muscle mass. None of these results was surprising—and the effects were similar in both age groups.

But HIIT was really a hit for the older set in the way it increased the activity of genes that are thought to improve mitochondrial function. Mitochondria are tiny power plants inside every cell. As we age, the mitochondria in our cells diminish in both quantity and quality…and that leads to reduced ability to convert oxygen and nutrients into energy.

In the older study group, muscle biopsies showed that nearly 400 genes that affect mitochondria became more active with HIIT. In the younger group, 274 such genes became more active. In the older exercisers, HIIT was particularly effective at reversing low activity levels of 11 genes that are known decline with age.

Bottom Line: HIIT is a great approach to fitness, especially if you’re older. Here’s the program that was used in the study…

  • Three days a week, exercisers pedaled stationary bikes—fast and hard for four minutes, followed by a three-minute interval of slow pedaling. They repeated that cycle for a total of four times.
  • Twice a week, on other days, they ran on a treadmill at 70% of capacity for 45 minutes. That’s not interval training, but it rounded out the weekly aerobic program.

If this program seems intense, that is because it is! Although the study didn’t look at less intense intervals, do what you are comfortable doing and work your way up. You may not reap the same benefit of the study participants right off the bat, but you will be on the right track. A good place to start is with this guidance from The American Council on Exercise.