Why To Exercise — Intensely — Today: The 'Afterburn'

The advice from experts is clear: Any exercise is better than none, and merely moderate exercise, like a brisk walk, is great for your health in myriad ways. But there's also a special magic to intense exercise, and a study just featured in The New York Times here highlights one aspect of it: It appears to spur the mythical "afterburn." That is, after intense exercise, your body keeps burning extra calories. Gina Kolata writes:

Whether the metabolism speeds up for hours after exercise is an old question, first studied a century ago, and over the years, study after study has been carried out, with decidedly mixed results. Some investigators found no post-exercise effect. Others reported effects so small they were almost unnoticeable — one found male triathletes burned just 12 to 30 extra calories after a workout. Others found as many as 700 additional calories were burned after a long and exhausting exercise session.
The latest sally comes in a recent paper in the journal Medicine & Science in Sports & Exercise. Its lead author, Amy A. Knab of Appalachian State University, says it trumps studies that preceded it because of its careful design.

The study involved ten men put in a "metabolic chamber" that measured how many calories they burned and asked to ride stationary bikes for 45 minutes so vigorously they were breathing too heavily to chat. The findings:

The exercise itself burned about 420 calories, Dr. Knab and her colleagues reported. But what was most interesting was the calories burned afterward. Over the next 14 hours, the men burned an extra 190 calories, increasing the total calories burned by 37 percent. “We were surprised,” Dr. Knab said. She thought there might be extra calories burned, but she did not expect so many, nor did she expect the effect to last so long. She suspects one reason she saw such a pronounced effect was that the exercise was so intense.


The story includes other evidence that exercise intensity leads to afterburn. Hmm. I''m feeling like today might be an interval-training day...

This program aired on April 19, 2011. The audio for this program is not available.

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Carey Goldberg Editor, CommonHealth
Carey Goldberg is the editor of WBUR's CommonHealth section.



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