A recent study found that three 10-minute spurts of exercise are more effective than 30 minutes of continuous activity at reducing fat in the blood, which may reduce heart-disease risk. A lift in metabolism, or the speed at which your body burns calories, may be why. "After each short exercise bout, resting metabolism increased slightly," says study coauthor Thomas Altena, assistant professor at Southwest Missouri State University. "If these sessions are performed regularly throughout the day, with about two to four hours in between, resting metabolism may remain elevated." This study focused on beginning exercisers, but Altena finds these results encouraging for everyone.