EPOC And Its Effects On Training, Hormones And The Body

Written by Jamie Bantleman

What Is EPOC?

EPOC is an acronym for Excessive Post-Exercise Oxygen Consumption. Often known as oxygen debt, EPOC refers to the period of time post-workout where we are working to restore normal oxygen levels. We also burn more calories due to the workout increasing your metabolic rate.

EPOC is a way in which we lose body fat, but how exactly is this achieved? Well, there are different ways to do this. Although aerobic exercise can cause EPOC to act for longer, we are looking at achieving it through performing moderate to high-intensity resistance training. You should also look at the use of triglycerides and fatty acids as opposed to carbohydrates as an energy source for a prolonged effect.

“Differences in exercise mode may potentially contribute to the discrepant findings of EPOC magnitude and duration. Studies with sufficient exercise challenges are needed to determine whether various aerobic exercise modes affect EPOC differently. The relationships between the intensity and duration of resistance exercise and the magnitude and duration of EPOC have not been determined, but a more prolonged and substantial EPOC has been found after hard- versus moderate resistance exercise. Thus, the intensity of resistance exercise seems to be of importance for EPOC.”

Studies in the past have been inconclusive in terms of whether or not EPOC is a necessity for achieving fat loss. It was thought that prolonged states of EPOC had a thermogenic effect on the body, therefore enabling you to lose body fat. However, in more recent studies we have found that certain protocols are much more effective on EPOC. Evidence has accumulated to suggest an exponential relationship between exercise intensity and the magnitude of the EPOC for specific exercise duration. Furthermore, work at exercise intensities more than or equal to 50-60% VO2max stimulate a linear increase in EPOC as exercise duration increases.

Strength training with compound, multi-joint 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 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. 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 ATP is 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.

Achieve greater levels of EPOC with this training plan: