You can finally ditch that “no time for exercise” excuse. A growing body of evidence shows it takes less time than you think to get in shape.
Take the recent University of the West of Scotland study where investigators asked one group of teens to run on a treadmill three times a week at a steady pace for 20 minutes and another group to do a series of brief, all out sprints. After seven weeks, both groups showed significant cardiovascular improvements including better aerobic fitness (a measure of cardiovascular health) and lower BMI—but the sprint group invested only 15 percent of the time to get nearly the same benefits (63 minutes versus 420 minutes.)
If you want to give shorter, faster workouts a try, Olson advises being diligent about warming up and cooling down properly. Also, space out your high-intensity sweat sessions to give your body several days to rest and recover. To find a high-octane training program that’s right for you, click through our gallery of seven popular, kickass workouts.