1. DURING THE IMMEDIATE POST-EXERCISE RECOVERY PERIOD, OXYGEN IS USED FOR THE FOLLOWING FUNCTIONS:
- Production of ATP to replace the ATP used during the workout
- Resynthesis of muscle glycogen from lactate
- Restore oxygen levels in venous blood, skeletal muscle blood and myoglobin
- Work with protein for the repair of muscle tissue damaged tissue during the workout
- Restore body temperature to resting levels
2. EXERCISE THAT CONSUMES MORE OXYGEN BURNS MORE CALORIES.
The body expends approximately 5 calories of energy (a calorie is the amount of energy required to heat 1 liter of water 1 degree centigrade) to consume 1 liter of oxygen. Therefore, increasing the amount of oxygen consumed both during and after a workout, can increase the amount of net calories burned.
3. CIRCUIT TRAINING AND HEAVY RESISTANCE TRAINING WITH SHORT REST INTERVALS REQUIRE ATP FROM THE ANAEROBIC PATHWAYS, LEADING TO A SIGNIFICANT EPOC EFFECT.
Strength training with compound, multijoint weightlifting exercises or doing a weightlifting circuit that alternates between upper- and lower-body movements places a greater demand on the involved muscles for ATP from the anaerobic pathways. Increased need for anaerobic ATP also creates a greater demand on the aerobic system to replenish that ATP during the rest intervals and the post-exercise recovery process. Heavy training loads or shorter recovery intervals increase the demand on the anaerobic energy pathways during exercise, which yields a greater EPOC effect during the post-exercise recovery period.
4. HIGH-INTENSITY INTERVAL TRAINING (HIIT) IS THE MOST EFFECTIVE WAY TO STIMULATE THE EPOC EFFECT.
The body is most efficient at producing ATP through aerobic metabolism; however, at higher intensities when energy is needed immediately, the anaerobic pathways can provide the necessary ATP much more quickly. This is why we can only sustain high-intensity activity for a brief period of time—we simply run out of energy. HIIT works because during high-intensity exercise ATP is produced by the anaerobic pathways; once that ATP exhausted, it is necessary to allow ATP to be replenished. The rest interval or active-recovery period during an anaerobic workout allows aerobic metabolism to produce and replace ATP in the involved muscles. The oxygen deficit is the difference between the volume of O2 consumed during exercise and the amount that would be consumed if energy demands were met through only the aerobic energy pathway.
5. EPOC IS INFLUENCED BY THE INTENSITY, NOT THE DURATION OF EXERCISE.
Higher intensities require ATP from anaerobic pathways. If the ATP required to exercise at a particular intensity was not obtained aerobically, it must come from the anaerobic pathways. During EPOC, the body uses oxygen to restore muscle glycogen and rebuild muscle proteins damaged during exercise. Even after a HIIT workout is over, the body will continue to use the aerobic energy pathway to replace the ATP consumed during the workout, thus enhancing the EPOC effect.
6. RESEARCH HAS SHOWN THAT RESISTANCE TRAINING CAN PROVIDE A GREATER EPOC EFFECT THAN RUNNING AT A STEADY SPEED.
In an extensive review of the research literature on EPOC, Bersheim and Bahr (2003) concluded that “studies in which similar estimated energy cost or similar exercising VO2 have been used to equate continuous aerobic exercise and intermittent resistance exercise, have indicated that resistance exercise produces a greater EPOC response.” For example, one study found that when aerobic cycling (40 minutes at 80 percent Max HR), circuit weight training (4 sets/8 exercises/15 reps at 50 percent 1-RM) and heavy resistance exercise (3 sets/8 exercises at 80-90 percent 1-RM to exhaustion) were compared, heavy resistance exercise produced the biggest EPOC.
7. THE EPOC EFFECT FROM A HIIT OR HIGH-INTENSITY STRENGTH-TRAINING WORKOUT CAN ADD 6 TO 15 PERCENT OF THE TOTAL ENERGY COST OF THE EXERCISE SESSION.
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 (LaForgia, Withers and Gore, 2006).
Admittedly there is some debate about the significance of the EPOC effect for the average exercise participant because the high-intensity exercise required for EPOC can be extremely challenging. However, if you want results and are up for the challenge, increasing the intensity of your workouts by using heavier weights, shorter rest intervals or high-intensity cardio intervals may be worth the effort. While HIIT or heavy resistance training is effective and beneficial, remember to allow at least 48 hours of recovery time between high-intensity exercise sessions and try to limit yourself to no more than three strenuous workouts per week. If you do start increasing the intensity of your workouts to boost EPOC, consider adding these recovery strategies.