If the word sprint makes you hyperventilate, relax: You don’t need to go all out to get the fat-burning benefits of cardio intervals, says The Journal of Physiology.
Simply pushing yourself out of your comfort zone will fire up your cells’ energy factories, says lead investigator Martin Gibala, Ph.D., of McMaster University in Canada.
Whether you’re swimming, biking, or running, try this: On an effort scale of 1 to 10, if you feel comfortable at 5, rev up to 7 for a minute, then do a minute at an easy pace. Work up to 10 intervals.