B O S T O N, Aug. 28 -- A few butt-squeezes here, a few stomach crunches there. Could intermittent exercise really be as effective as a full 30-minute workout in one sitting?
Yes, say Harvard researchers, reporting in the current issue of Circulation, the journal of the American Heart Association. As long as the total energy expended is the same, it may not matter whether you divide your workout into short bursts throughout the day or complete it in one marathon session, they determined.
Previous research has found that discontinuous workouts can improve fitness and cholesterol levels, but it was unclear whether the long-term risk of heart disease would be lower as well.
To find out, researchers, led by epidemiologist I-Min Lee at the Harvard School of Public Health, studied 7,307 male Harvard alumni from 1988 to 1993, tracking the amount of time the men exercised, played sports or simply climbed a flight of stairs in the course of a year.
The study looked only at men in their 60s, but researchers said they plan to study whether the effect holds true in women as well.
Heart Disease Unaffected Researchers found the risk for coronary heart disease was the same whether the men exercised in several short periods throughout the day, or completed their workouts in one time period, provided the energy output was the same.
“Physical activity does not have to be arduously long to be beneficial,” says Howard D. Sesso, an epidemiologist at the Harvard School of Public Health and a co-author of the report. “Short sessions lasting 15-minutes long appear to be helpful. If you are unable to set aside 30 minutes all at once for exercise, try two 15-minute sessions.”
The findings challenge the mantra once touted by many workout mavens, which states you need at least 20 continuous minutes of sweat-inducing intense activity three times a week, or 30 continuous minutes of moderate activity daily to get any health benefits.
“Intense” activities include tennis and running, while more “moderate” activities might include yard work, social dancing or golfing.