HIIT is a short form of high intensive interval training. High intensity interval training (HIIT) has the fitness industry buzzing because of its potential to torch maximum calories in a minimum amount of time. The idea is that you do short periods of all-out work followed by short periods of active rest to make the body work harder than it does during steady-state cardio. By having those rest intervals, you spend more time in the upper end of aerobic capacity, whereas you wouldn’t be able to do that if you tried to do 10 minutes of really high-intensity exercises. It’s going to have positive physiological adaptations, including improved fat buring, insulin sensitivity, and skeletal muscle oxidation.