The Power of EPOC at Orangetheory Fitness

Also known as Excess Post Exercise Oxygen (O2)Consumption, or the exercise afterburn, when one creates a state of EPOC, (s)he increases the uptake of O2 following a heavy bout of physical activity to repay the O2 debt that was created.1  Think of it as a credit card that accrues debt.  To pay off debt, one must work hard to increase the cash flow to pay it off.  The body operates the same way, only it increases the O2uptake to pay off the O2 debt, thereby improving one’s metabolism which can in turn create a thermogenic (fat burning) effect.2

This appears to be the most popular craze not only for athletes but for the average exerciser.  Everyone claims that they want to burn more fat, but don’t know how to.  The HIIT model, Tabata method, and Crossfit methodology became popular as a result.  However, none of these modalities stress the importance of target heart rate training, unless the individual trainer coaches the students to even use a heart rate monitor.  Orangetheory Fitness, on the other hand, puts that emphasis on target heart rate training in all of its studios to help promote that EPOC effect.  That is their orange zone or zone 4, where a student achieves 84-91% of his/her maximum heart rate.  The only way for any students to know this, is that they are all required to wear heart rate monitors and pay close attention to their active heart rateall throughout the duration of each class.

Because individuals have different target heart rate zones, it is essential that each individual trains within their own zone.  Without knowing where their heart rate is, it is virtually impossible to know whether they fall within their heart rate training zone or not.  When one achieves 84-91% of their max heart rate for approximately 10-20 minutes within a 45 minute to an hour of activity, (s)he can achieve EPOC.  However, the rest of their time should be spent training at approximately 65-78% of their max heart rate to help them recover from the push of the higher heart rate zone.  This entire training style can promote EPOC which elevates the consumption of fuel to pay off the O2 debt as mentioned previously. In response to EPOC, fat stores are broken down and free fatty acids (FFA) are released into the blood. In recovery, the direct oxidation of free fatty acids as fuel takes place.2,3 This appears to be the common goal in most gym goers.

In Breaking the Chains of Obesity, 107 Tools, tool # 43 provides interval programs that help achieve EPOC.  The trick is to plug in your numbers into the following formula to understand what your lower and upper zones are.  For example:

220-age-resting heart rate (65%) + resting heart rate= Lower Zone

220-age-resting heart rate (85%) + resting heart rate=Upper Zone

The best time to get a resting heart rate is first thing in the morning by counting the beats at your carotid artery for 30 seconds and multiplying by 2.  By discovering and using these two values, you can certainly achieve EPOC.  (I used 65% and 85% of one’s max heart rate as examples).

The great news is, you can use any modality of exercise to achieve this type of response.  For example, you can use a Spin® bike, treadmill, rowing machine, and elliptical.  Simply follow a program that achieves your lower and upper zones all within one workout.  Below is a sample workout to try:

Warmup for 5-8 minutes

Increase your speed or resistance to bring your heart rate to your upper zone for 1 minute

Recover at your lower zone for 1 minute

Go back and forth 5 times between your upper and lower zones.

Recover at your lower zone for 2 full minutes.


For more programming, please reference this former article written back in February 2014.



1) Scott CB, Kemp RB (January 2005). “Direct and indirect calorimetry of lactate oxidation: implications for whole-body energy expenditure”. Journal of Sports Sciences23 (1): 15–9.

2) Bahr R, Høstmark AT, Newsholme EA, Grønnerød O, Sejersted OM (September 1991). “Effect of exercise on recovery changes in plasma levels of FFA, glycerol, glucose and catecholamines”. Acta Physiologica Scandinavica 143 (1): 105–15

3) Bielinski R, Schutz Y, Jéquier E (July 1985). “Energy metabolism during the postexercise recovery in man”. The American Journal of Clinical Nutrition 42 (1): 69–82.