The high-intensity interval training (HIIT) method involves short intervals of high-intensity work — training near 90 percent maximum heart rate (MHR) — followed by intervals of slower-pace active recovery. “To keep your body guessing [and the scale moving], you have to either add more cardio or increase the intensity,” IFBB fitness pro Allison Ethier says. “Most people don’t have time during the week to devote to multiple cardio workouts. Adding a few hard HIIT sessions will get the job done and save a lot of time.”
The Burning Edge: Research confirms the shorter-duration HIIT method is superior to steady-state cardio for losing fat. In a landmark 1994 study published in the journal Metabolism, researchers had one group follow a 15-week HIIT program and another perform only steady-state cardio for 20 weeks. The data revealed that the steady-state group burned 15,000 more calories but the HIIT group lost significantly more bodyfat.
A more recent study conducted at the University of New South Wales (Australia) reported that a group of women who took part in a 20-minute HIIT program of eight-second sprints followed by 12 seconds of rest lost six times more bodyfat than a group that did steady-state cardio for 40 minutes at 60 percent MHR. And that’s not HIIT’s only fat-fighting benefit. The increase in intensity boosts the metabolism and keeps it higher longer after your workout is over. This is known as EPOC, or the afterburn effect, which in part helps fuel the repair of exercise-induced damage.
Research on subjects using either low-intensity protocols or the HIIT method found that the HIIT group burned an average 10 percent more calories in the 24 hours following exercise than the low-intensity groups, even though the total calories burned during each workout were the same. So if you train intensely enough, you’ll burn calories just sitting on the couch afterward.
Burn 500 in: 32 minutes
Tip: Keep your HIIT workouts fresh by taking it outside with exercises such as jumping jacks, jump rope, hill or stair sprints and jump squats. Whatever you choose, you’ll need to perform 90 seconds of high-intensity work followed by 30 seconds of slower-pace recovery for a total of 32 minutes (including warm-up and cool-down). But Ethier cautions: “You’ll want to ease into this type of cardio training. To start, try doing 10 seconds of hard work followed by 50 seconds of recovery. By starting off slowly, you’ll be able to determine how much your body can handle in one session and avoid injuries.”