What to know about EPOC?
Excess Post-exercise Oxygen Consumption. Also known as oxygen debt,
EPOC is the amount of oxygen required to restore your body to its normal, resting level of metabolic function (called homeostasis). It also explains how your body can continue to burn calories long after you’ve finished your workout.
Similar to how a car’s engine remains warm after being turned off, once a workout is over and you’re back in your daily routine, your body’s metabolism can continue to burn more calories then when at complete rest.
The EPOC effect from HIIT. High-intensity workouts require more energy from the anaerobic pathways and can generate a greater EPOC effect, leading to extended post-exercise energy expenditure.
Heavy weight training and HIIT workouts appear to be superior to steady-state running or lower-intensity circuit training in creating EPOC
Recovery Once you stop exercising, the process of recovery starts immediately.
The extra energy is used in many recovery processes. One major requirement is to remove most of the lactic acid (as a chemical by-product, it needs to be cleared and converted into a useful energy source).
The synthesis pathway to turn lactic acid back to glucose (then glycogen) costs energy and is an important function of the liver.
Summary It’s unlikely EPOC is the only beneficial after-effect of exercise, and the benefits of HIIT metabolically are still poorly understood. The question of why HIIT seems to burn more fat than other forms of exercise definitely warrants more study.
Also, EPOC varies between different people and scientists cannot yet pinpoint the reasons for this variation (although it seems not to be influenced by fitness, fatness or gender).