H.I.I.T (High Intensity Interval Training) is a training technique which utilises quick, intense exercises done in quick succession. This ensures that your heart rate is kept high which causes fat to burn faster. After these workouts, you tend to feel the afternburn, which is your body craving for more oxygen during recovery. Hence, you burn more fat and calories. To optimise these workouts, it is important to maintain a ratio of work to recovery times.