What exactly is EPOC and how does it affect you?
I am sure that most of you have heard of the “fat burning zone” as it relates to cardiovascular and strength training exercises. If you haven’t, the theoretical “fat burning zone” is working out at a rate of 60 – 75% of your maximum heart rate during exercise. Now at this heart rate your body does burn more of its calories from fat. The problem is that you aren’t burning that many calories when you are working out at this level, so in the end, you really aren’t burning much fat. All of the cardiovascular equipment manufacturers simply put those programs on their machines so that the consumer will purchase it. Nothing more, nothing less.
The truth of the matter is that you need to burn more calories than you eat to sustain weight loss. By working out at high intensities, your body will burn more calories during and after your exercise session.
What is the Exercise After-burn or EPOC?
The exercise after-burn, or the calories expended (above resting values) after an exercise bout, is referred to as ‘excess post-exercise oxygen consumption’ or EPOC. This represents the oxygen consumption above resting level that the body is utilizing to return itself to its pre-exercise state.
EPOC and Cardiovascular Exercise Intensity
The intensity in an aerobic exercise bout has the greatest impact on EPOC. As exercise intensity increases, the magnitude and duration of EPOC increases. Therefore, the higher the intensity, the greater the EPOC and the greater the caloric expenditure after exercise.
The training status of an individual may also have an effect on EPOC. Studies are inconclusive but suggest that trained individuals recover from exercise faster than their untrained counterparts. One reason for the inconsistencies in the research is that it is difficult to match exercise intensity and total work performed for trained and untrained individuals. If matched relative to fitness level, the trained individual would be working at a higher intensity than the untrained individual. Several studies have reported a more rapid fall in EPOC and a shorter duration of EPOC in trained subjects. Even though people with higher fitness levels appear to have a faster recovering EPOC, due to their generally higher training intensities and duration the magnitude of their EPOC is still quite prominent.
Gender and EPOC
Gender is also a factor that may influence EPOC. Research shows that energy expenditure with women at rest and during exercise varies with the menstrual phase. Typically, resting energy expenditure is lowest one week before ovulation and highest during the 14-day luteal phase following ovulation, thus accordingly affecting EPOC.
Few controlled studies have been conducted to compare EPOC in men and women. Therefore the gender effect on EPOC is not fully known.
Although there appears to be variation in individual responses, the positive news is that any additional caloric expenditure following exercise can add up over time and may contribute to long-term weight management. If you want to maximize energy expenditure through EPOC, focus on developing your training status so you can perform higher intensity exercise for periods of 30 minutes or more. In addition, regularly incorporate interval training workouts, as this type of training positively enhances EPOC. Most of the current literature supports exercise intensities at or above 70% of VO2 max for optimal energy expenditure following exercise. Additionally, encourage yourself to engage in resistance training at least 2 times a week. Not only will resistance training maintain or increase muscle mass in weight-loss interventions, studies report a meaningful EPOC effect following high intensity and circuit resistance training.