This article is all about the relatively new exercise method, called HIIT, high intensive interval training. This hiit method consists of a period of intense exercise, followed by a period of low intense exercise, or simple rest. This type of training seems, based on research, to be more efficient, in terms of fat burning, weight loss, increased strength and stamina,than the traditional steady state exercise (classic cardio workout). One of its best "features" is that it lowers insulin resistance and increases oxygen intake. It is a workout based on studies conducted by health professors, and it is considered to be safe for all levels of health and fitness. That is because the intensity of exercise can be adjusted according to every hiit practitioner. At the end of the article there are listed indicatively two hiit workout routines, one for beginners, and one for intermediate fitness level.