High intensity interval training or HIIT is an effective way to maximize calorie burn in a shorter amount of time. HIIT is heart rate based training, we elevate our heart rate attempting to get to our anaerobic threshold and this would be followed by a complete recovery. An example would be a 30 second max effort sprint immediatelt followed by a one to two minute walk to recover the heart rate. This spike and lowering of our heart rate maximizes our calorie burn during the workoit as well as after. During the max effort we will create a debt of oxygen in the body, and we will continue to burn calories for up to 36 hours after the HIIT training attempting to recover the debt of oxygen. The max effort sprints also activate our fast twitch muscle fibers, which are contained in our larger muscles in turn burninf more calories while working and at rest.