High-intensity interval training is the No.1 fitness trend in the world, according to the American College of Sports Medicine's Worldwide Survey of Fitness Trends for 2014. What makes the training method so popular is the efficiency of the fat-burning workouts; they only take a few minutes to complete. HIIT is a workout style comprised of short work periods followed by short rest periods. “Using HIIT, you’re going to burn the most calories in the shortest amount of time,” says Tom Holland, a Connecticut-based exercise physiologist and designer of the workout below. “Mixing cardio and strength training at a high intensity gives you the ultimate full-body workout.” 

Directions

Perform the warmup then start the workout. Recovery is jumping rope at 50% of maximum heart rate. Do this workout for three rounds for a total of 30 minutes, including work and recovery.

Warmup

Jump rope, jumping jacks, high knees, or any type of cardio.
Duration: 3-5 min.

The workout

Jump lunge
Duration: 1 min.
Recovery: 1 min. of jumping rope

Box jumps (Box should reach knee height)
Duration: 1 min.
Recovery: 1 min. of jumping rope

Dumbbell renegade row with pushups
Duration: 1 min.
Recovery: 1 min. of jumping rope
Tom says: Starting in pushup position, row one dumbbell. Return to pushup position. Row the other dumbbell. Return to pushup position. Do a pushup. That’s one rep.

Dumbbell power jerk
Duration: 1 min.
Recovery: 1 min. of jumping rope
Tom says: Perform a quarter squat with dumbbells at shoulder level, then press both dumbbells over your head. Return to start.

Dumbbell uppercuts
Duration: 1 min.
Recovery: 1 min. of jumping rope
Tom says: Perform a squat while holding the dumbbells at your side. Punch up and across your body with one arm. Repeat with other arm.