FITNESS

Five moves, four sets, lots of burn. Shake up your go-to HIIT workout with this energizing circuit and you'll not only burn tons of calories but also take your firming—and fitness—up a level. Because your muscles get worked every which way as you go low, jump high, run fast, lift weights, and change directions—all in the same session-you reap incredible sculpting and afterburn benefits, say Kirk Dewaele and Brandon Cullen, the cofounders of MADabolic Inc., a studio in Charlotte, North Carolina, known for its HIIT workouts that emphasize variety. Their fresh approach rolls primal movements (squatting, jumping, crawling), power, strength, cardio, and rotation into every class. Incorporating strength in your HIIT workout like this torches calories on the spot and improves your muscle function enormously by stimulating muscle growth and development. New research in the journal Applied Physiology, Nutrition, and Metabolism found that the technique helped exercisers subsequently