High Intensity Interval Training is a form of cardio-strength functional exercise strategy, alternating short periods of intense anaerobic exercise to the point of momentary muscular failure with less intense recovery periods to maximize the amount of muscle fiber recruitment. HIIT increases strength, speed and VO2 Max, furthermore it speeds up  your metabolic rate for as long as 38 hours, while giving you a full body workout that maximizes fat and calorie burning.