EPOC occurs after both aerobic and anaerobic exercises. However, anaerobic training has been shown to produce greater EPOC than aerobic training, due to it’s higher intensity. More specifically, current studies have shown that high intensity interval training (Halton et al. 1999), as well as heavy resistance training (Burleson et al. 1998), both produce greater EPOC compared to aerobic training. And the greatest EPOC resulted from intermittent, high intensity weight training (Melby et al. 1993; Laforgia et al.  1997). The reason maybe that it causes the largest deficit to homeostatic levels in the body compared to any other activities and therefore greater energy and time is required to restore the body back to pre-exercise state. So the more we jolt our body by performing hard intervals or lifting heavy weights, the more calories we end up burning after the training session to make up for all the disruptions we caused to our body’s balanced state.
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Some of the physiological mechanisms involved that cause EPOC are as follows:
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(1) Restoration of various energy sources which include:
- Re-phosphorylation of ATP-CP. (ATP is the body’s basic energy source)
- Removal of lactic acid. Lactic acid which was produced by the high intensity activity, is converted to pyruvate so that it can be transported back into the Krebs cycle for further energy production.
- Replenishment of glycogen (stored form of glucose) in the skeletal muscles.
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(2) Re-oxygenation and restoration of blood and circulating hormones
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(3) Re-establishment of normal ventilation and heart rate
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(4) Restoration of normal core body temperature
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All these mechanism involve energy, which means more calories burned. This is why EPOC has been associated weight loss and weight management applications. Some studies have noted that we can burn calories for up to 48 hours after an intense exercise session. Hence, EPOC is sometimes referred to as the “”after burn”. Recent studies have also concluded that duration of the intense exercise also has direct correlation to EPOC. The longer you can train at a high intensity, the greater the effect of EPOC. This ties in nicely with the Werkout philosophy of fitness. Although intensity is relative, it can be assumed that the more “work” performed in a given period of time, the greater the intensity of effort. Therefore, training to improve work capacity will also result in greater EPOC as just one of many beneficial physiological effects. After a hard training session you can rest assured that your body is working overtime burning up the calories!