No time to exercise? That’s what you think.

Research shows that high-intensity interval training—brief bursts of activity followed by short rests or recovery periods of low-intensity activity—often yields greater benefits, in less time, than a conventional, moderately paced workout.
“You can get away with doing less interval training compared with a continuous workout,” says Jonathan P. Little, assistant professor in the school of health and exercise sciences at the University of British Columbia. “There’s more bang for your buck.”

For many people who don’t have the time—or the patience—for a long workout, the findings will be welcome news. In addition, knowing the benefits of high-intensity interval training, or HIIT, could make it easier to stick with an exercise regimen. A special attraction for older exercisers: The training may be better than noninterval aerobic exercise for chronic conditions that tend to afflict older people, such as heart disease, diabetes and pulmonary disease.

HIIT forces the heart and lungs to work harder in the “sprint” mode than they would in a typical workout, which leads to greater gains in aerobic capacity. The approach causes more blood to flow through the body, making blood vessels particularly elastic, and requires work from more of your muscles.

“When you go out for an easy walk, you call upon about 50% to 60% of your muscle fibers,” Dr. Little says. “To do the work at a quicker pace calls upon 80% to 100% of your muscle fibers.”

The interval approach is popular among young elite athletes who want to improve their performance, but other people are beginning to see benefits. Much of the data involves people over 50 years of age, who stand to reap more of its benefits; after 50, people start losing muscle mass, especially the fast-twitch fibers that enable everyday activities like climbing stairs or recovering from a stumble. HIIT may be particularly appealing to those who have never logged miles on a treadmill or counted laps in a pool.

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