'HIIT' or High Intensity Interval Training involves short bursts of high intensity movement followed by short periods of rest. These workouts are usually done in a 'circuit style' format where there are 3-4 blocks of workouts each consisting of 3-4 movements within each. Each movement within the block is performed for a period of time and followed by a shorter period of rest immediately after. Each block will have longer rest times between them. This style of workout is typically very cardio intensive with lots of explosive movements such as box jumps and burpees.