Why interval training may be the best workout at any age

High-intensity interval training (HIIT) is not just for the young and healthy. Researchers have found that HIIT can improve health and fitness for just about everyone and has even bigger benefits for older adults.

The concept of "HIIT" is pretty simple. You can do anything for 30 seconds or even a couple of minutes. And then, given a chance to catch your breath, you'll be able to do it again. During a HIIT workout, you alternate between exerting a high and low level effort of exercise.

It may protect cells from aging

Mayo Clinic researchers studied the effects of HIIT on people over age 65. What they discovered may surprise you: Some age-related deterioration of muscle cells had actually been reversed.

HIIT seemed to change a cell's DNA in a way that boosted the muscle's ability to produce energy. It also triggered the growth of new muscle, helping counteract inevitable muscle loss that comes with aging.

These changes were more dramatic in the over-65 exercisers compared with a group of people under age 30 who did the same workouts. One possible takeaway: It's never too late to start and see big gains.

It's simpler than you think

Interval training doesn't require special training or equipment. In one study, walkers who added higher-intensity intervals to their walking program improved their aerobic fitness, leg strength and blood pressure. They did it by simply alternating between three minutes of fast walking and three minutes of slow walking for 30 minutes or more four times a week.

Peers who walked twice as long but at a moderate, consistent pace made minimal gains in fitness or other measures — similar to a comparison group that didn't exercise at all.

It can get you hooked on exercise

If you've been looking for that elusive workout that will turn you into a regular exerciser, interval training may be it. In the interval walking study, every single participant kept up with the goal of four interval walking workouts a week for four months.

After nearly two years, they still averaged more than three workouts a week, an impressive stick-with-it rate for any workout program.

One reason: It can be fun to push yourself. Researchers have observed that people prefer high-intensity intervals and say they are likely to stick with routines that include them.

It's compatible with many health conditions

It's always a good idea to check in with your doctor before starting a new workout routine, especially if you have an ongoing health condition. But many studies have concluded that intervals can be safe and beneficial for people with diabetes, heart disease and more.

In one study, people with heart disease who alternated between fast and slow pedaling on an exercise bike (20 and 40 seconds, respectively) improved how fast their heart rates slowed to normal after exercise. This is considered an important marker for longevity.

Still, every workout shouldn't be HIIT

Many experts recommend just one or two interval workouts a week combined with light or moderate exercise in between. That's important because the time between hard workouts allows your body to rebuild bones and muscles to increase strength. Plus, you may not want to push your body to its limit every day — and that's OK. There are plenty of benefits to taking a walk with a friend, too. It's about balance.