HIGH-INTENSITY INTERVAL TRAINING High-intensity interval training, involving short bursts of intense exercise grouped with low-intensity recovery periods, is perhaps the most time-efficient way to exercise. This type of workout often ranges from ten to thirty calorie-burning minutes, speeds up your heart rate, and can produce health benefits twice that of moderateintensity exercise. Workouts vary and can include bodyweight exercises such as sprinting, biking, or rope jumping. Sprinting up a flight of stairs followed by a walk back down is interval training. Runners have been interval training for centuries, alternating between sprinting and jogging to improve endurance.