EPOC: What is it?

What is EPOC? EPOC stands for Excess Postexercise Oxygen Consumption. Okay, so you got that, but what exactly does that mean? When you start to do work, no matter what it is, the body needs more energy to complete the task. The energy just used to do the work needs to be replaced, and depending on the intensity and duration will determine  what energy system(s) are used. Then the body must increase its metabolism to help recover the energy it just used.

If you are training at a rate that is below your VO2 max there is an initial lag where oxygen consumption is not equal to the oxygen needed to perform the work. Once the body is able to catch up to the oxygen needed to maintain that level of work there is a plateau in oxygen consumption. Once your body returns to a resting state there is a deficit of oxygen consumption derived from the initial work. The body makes up for this by consuming more oxygen, for a while after, once at rest. The amount of time the body increases oxygen consumption after varies from how long there was an initial lag.

If you are training at a rate that is at or above VO2 max there is still an initial lag for the oxygen consumption to catch up, but never reaches the required amount to sustain that level of work. Since the body was working at above VO2 max there is a larger oxygen deficit, than working below VO2 max. The body will consume more oxygen after returning to rest for a longer period of time than working below VO2 max.

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The cause for this initial lag is of oxygen consumption is caused by the varying reaction times of the different energy systems within the body. What are these systems? ATP-PC is stored energy within the muscles that when work is initiated is the first energy system to be used up. Anaerobic glycolyis will start to occur, which is a fancy way of saying the body uses stored carbohydrates, and oxygen to create ATP (energy) for the muscles to use. If the rate is steady, and long enough then fat metabolism will occur where fat is broken down in the body, and used as energy.

Other factors of EPOC are elevated hormone levels, that cause the body to utilize fuel in the body until the hormones are cleared from the body. An elevation in body temperature, for every one degree the body core temperature goes up metabolic rates increase 13-15%. And the removal of lactate from the muscles. EPOC occurs during physical activity running, lifting weights, or even just going for a walk. The benefits of exercise do not stop when you stop working out, they continue even when you are done since your body still burns more energy than at rest.  Keep that in mind next time you are working out!

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Steven Moore About Steven Moore

Passionate Personal Fitness Trainer, and NASM Corrective Exercise Specialist at Blitz Conditioning. Prone to spurts of random nonsense. [Read my full bio]

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