high intensity interval training

High-Intensity Interval Training May Not Save Time

High-intensity interval training (HIIT) has captured a lot of attention lately because of its simple message: If you exercise hard enough, you can get just as fit in less time.

Even the U.S. Department of Health and Human Services buys this concept to some degree. It recommends at least 2.5 hours per week of moderate exercise, but it also says a minute of vigorous exercise equals two minutes of moderate exercise. 

(For an idea how different types of activity compare, take a look at this chart from Harvard Health Publications.)

The promise of cramming more exercise into less time has led many books and websites to promote five-minute workouts.

But few studies have compared high-intensity interval training directly to other exercise programs, and also examined how well participants enjoy them.

At the American College of Sports Medicine meeting last month, I heard Courtney Farland, a researcher from the University of Wisconsin in La Crosse, describe how her team did just that.

High-Intensity Interval Training Tested

They randomly assigned 55 untrained college-aged men and women to three groups. All the groups worked out three times a week for eight weeks on stationery bicycles designed to measure their exertion.

The “steady state” group pedaled to the point where they were panting really hard.They kept this up for 20 minutes.

The Meyer group pedaled so hard they consumed all the oxygen their bodies could take in. They kept this up for 30 seconds, then rested for a minute, then repeated the exercise and the resting for a total of 13 sets over 20 minutes.

The Tabata group pedaled 70 percent harder than the Meyer group. This may sound impossible. But every human being is capable of producing energy without oxygen for a short period of time.

And the Tabata group only kept up this frantic pace for 20 seconds. Then they rested for 10 seconds and repeated for a total of eight sets. Their exercise sessions lasted just four minutes.

At the end of the eight weeks, all the groups had increased their aerobic capacity by about 18 percent.

They had also increased the amount of energy they could generate by pedaling as hard as possible. The Tabata group increased its energy output by 9 percent, the steady state group increased by 8 percent and the Meyer group by 5 percent. But the differences among the groups were not statistically significant.

Does High-Intensity Interval Training Save Time?

The volunteers in the Tabata group did spend less time exercising to achieve these results, but the exercise was so intense, they tended to collapse afterward, said Farland. “A lot of those students were not ready to go to class after that. A lot of them spent some time on the floor with a juice box and some Jolly Ranchers.”

In fact, they spent so much time recovering Farland wasn’t sure they actually saved time by doing such short, intense workouts.

When the researchers interviewed the volunteers, they found that everyone liked the exercise less and less as time when on. The Tabata group liked their routine the least.

“We’re hoping to develop some exercise regimens that are more enjoyable because that’s the only way we’re going to keep the population exercising,” said Farland.

I wonder if she has ever tried sports?
For more technical details, see my Medscape article on this study.

Photo: “Aerobithon – U.S. Army Garrison Humphreys, South Korea – 19 May 2012” by USAG Humphreys.

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