Short training bouts add up.

Despite the best intentions, life can get in the way of your workout schedule from time to time. Work and family responsibilities, illness, and injury, to name just a few spoilers, can keep you from logging in the miles you've planned. But don't let a shortage of time undermine your fitness. New research supports the theory that exercise accumulated in several shorter bouts (as little as 10 minutes each) can have the same cumulative effect on the cardiovascular system as longer bouts.

Researchers evaluated the cardiovascular effects of three 10-minute bouts of exercise, two 15-minute bouts, one 30-minute workout, or no exercise for 30 female college students with a body mass index of 28 or higher (overweight). Exercise was conducted at 75% of maximum heart rate three to five days per week. For all exercise groups, VO2max increased significantly, while weight and body mass index decreased significantly.

While running in shorter training bouts won't get you marathon-ready, don't underestimate the benefits of doing what you can, when you can. As little as 10 minutes a day of moderate physical activity can produce significant benefits. Taking a short run can help you maintain your training gains when you're unable to do more.

(Journal of the American College of Nutrition, 2001, Vol. 20, pp. 494-501)