HIIT is a form of aerobic exercise (meaning ‘with oxygen’) and affects the cardiovascular system of the body.
Short but intense bursts of activity anywhere from 30 sec to 2 min are followed by a period of rest. The purpose is to get the heart pumping fast as quickly as possible, then drop it back down, then repeat.
Because the body cannot get into any rhythm it gets very uncomfortable, and as a result your heart will become stronger and more efficient, the oxygenated blood flow through your entire body will increase, lung capacity and VO2 max will increase, resting heart rate will drop as the body adapts to get fitter… and this process burns a whole heap of energy.
