HIIT stands for high-intensity interval training and is based on the philosophy that a higher exercise intensity in a shorter amount of time is more effective. HIIT focuses on short bursts of intense exercise followed by short periods of rest or lower-intensity recovery periods. It is considered the most time-efficient way to exercise, lasting between 10 to 30 minutes in duration. Activities typically performed include sprinting, biking, jump rope or other body weight exercises. For example, one round of a HIIT workout using a stationary exercise bike could consist of 30 seconds of cycling as fast as possible against high resistance, followed by several minutes of slow, easy cycling with low resistance. One hypothesis as to why HIIT improves aerobic fitness more than continuous types of exercise is that HIIT increases the amount of blood that is pumped out of the heart while training. The benefits of HIIT are: higher calorie burn in a short amount of time, meaning people can spend less time exercising; metabolic rate remains elevated for hours after exercise, meaning the body continues to burn calories after the HIIT exercise is finished; boosts fat loss; greater EPOC (excess post-exercise oxygen consumption), which is the muscles’ ability to use oxygen, in turn increasing endurance and stamina; HIIT can reduce heart rate, blood pressure and blood sugar. HIIT can be further broken down into two categories SIT (sprint interval training) and HIT (high intensity training). SIT is an intense interval training suitable for experienced athletes who have no contrary health conditions. It involves performing 3-5 intervals of very short maximal-intensity exercise working until exhaustion, followed by a prolonged recovery period. For example, 20-30 seconds of training followed by a 3-5 minutes rest. HIT is more suitable for the average gym goer. It involves training periods ranging from 30 seconds to three minutes, with 80-100% of the maximum heart rate with shorter recovery periods than SIT.