Harvard Health Letter

Vigorous exercise produces 'afterburn' bonus

One of the obvious rewards of exercising hard is that you burn up calories while you're doing it. That added calorie combustion helps you stay trim and may even help you lose weight, although you also have to watch the number of calories you put into your body.

Exercise scientists have found that vigorous exercise has an added bonus: an "afterburn" of revved-up metabolism — and the calorie-burning needed to supply it — that continues after the huffing and puffing are over. Some studies have indicated that this lasts 20 to 30 minutes and burns 30 or so calories, which is fine but really not all that impressive. But researchers in North Carolina have reported some results that are.

They recruited 10 young, healthy male volunteers and used a sophisticated metabolic chamber the size of a small bedroom to measure their oxygen consumption before, during, and after exercise. Oxygen consumption is a reliable indicator of metabolic rate and calorie expenditure. Not unexpectedly, the young men burned up an average of about 500 extra calories during 45 minutes of hard pedaling on a stationary bike. What was surprising was that their metabolisms remained elevated for the next 14 hours, even though they were inactive and even as they slept during the last three and a half hours. The study subjects each burned an average of 190 extra calories during those 14 hours, which is 40% of the extra calories they burned up while cycling.

To continue reading this article, you must login.
  • Research health conditions
  • Check your symptoms
  • Prepare for a doctor's visit or test
  • Find the best treatments and procedures for you
  • Explore options for better nutrition and exercise
Learn more about the many benefits and features of joining Harvard Health Online »