As a result of a session of any type of high intensity training (HIT), the subsequent recovery period involves an elevated consumption of oxygen to help restoring our metabolism to base levels. This process has been recognized as excess post-exercise oxygen consumption (EPOC).
After HIT, the recovery period involves the removal of lactate and hydrogen ions, increased activity in cardiac and pulmonary function, elevated body temperature, glycogen re-synthesis and increase in endorphins (2). This recovery period requires the replenishment of water to enhance nutrient and oxygen retention and transport, and Co2 (waste) removal. In addition, the regulation of temperature, restorage of pH levels, and electrolyte balance are needed to ensure proper nervous system and overall function.
As discussed on the previous article “Why is High Intensity Superior, “HIT has greater benefits, specifically because of EPOC. Fat is mostly burned at rest, through aerobic metabolism. Thus, during the recovery period, you can burn more fat if you endure HIT. On a recent study review of 44 peer reviewed scientific studies (1), findings suggest, after resistance training (weights), the duration and magnitude of EPOC, depends on the following variables:
1. Total volume (sets X repetitions X weight used)
2. Intensity or workload (% of weight used, based on your 1 repetition max (1RM))
3. Rest interval between exercises
4. Speed of movement
5. Exercise Order
EPOC represents the number of calories burned after exercise, above the regular, resting values, known as resting metabolic rate (RMR). Thus, the longer the duration and magnitude of EPOC, the greater caloric consumption at rest, after training = greater fat burning.
The conclusion of the review stated:
A) Volume of training affects EPOC’s magnitude and duration, while workload affects mainly magnitude of EPOC.
B) Rest intervals <1min increases EPOC’s magnitude
Everything indicates when your goal is fat burning, the best combination for training is high volume, high workload, short rest periods. In other words, circuit training! The next thing to consider will be the exercise order.
During a different study (3), EPOC was compared between two groups working on a bike ergometer:
Group 1: 3X 30 second maximum effort with 4-minute rest between sets.
Group 2: 30-minute cycling at 60% heart rate reserve (moderate intensity).
Oxygen consumption was measured in both groups, before exercise and after exercise, for 30 minutes.
Results:
Group 1 averaged a consumption of 7.5 L of Oxygen, burning 37.5 calories within 30 minutes after training and the oxygen consumption remained higher than baseline levels.
Group 2 averaged a consumption of 1.8 L of Oxygen, burning 9.8 calories within 30 minutes after training and oxygen consumption went down to baseline levels, within 6 minutes of the recovery period (1).
The intent of this article is to remind you of why I always consider circuit training as the best option for fat burning, and aerobic and anaerobic energy systems development. As general rules, to maximize EPOC and its benefits, such as increase fat burning, increase Vo2max (oxygen consumption capacity, which dictates level of aerobic conditioning), we should consider:
1. Lift heavy, without compromising form. Consider a workload that ensures the last 2 repetitions are really challenging.
2. At least 3 sets of 10 repetitions, of a minimum of 7-8 exercises. When workload is higher, obviously repetitions are lower, but usually more sets, as well.
3. Minimum rest between exercises, except for your “core lift” of each session. That is the first exercise during a session and should not be compromised with fatigue. We will discuss more about this later, but after the core lift, usually paired with an easier exercise such as abs, then you should include circuits, with extremely limited rest between sets and exercises.
4. When performing short duration “aerobic” based exercises, such as sprinting, gassers, rope jumping, rowing, biking, etc., ensure you give all your effort, each time!
Work hard, work smart!
Cheers,
Coach
References
1. Farinetti, P., Castinheiras Neto, A.G., Lima de Silva, N. (2013). Influence of Resistance Training Variables on Excess Postexercise Oxygen Consumption: A Systematic Review. Hindawi Publishing Corporation ISRN Physiology Volume 2013, Article ID 825026, 10 pages.
2. Tomlin D.L. and Wenger, H. A. (2001). The relationship between aerobic fitness and recovery from high intensity intermittent exercise. Sports Medicine, vol. 31, no. 1, pp. 1–11.
3. Townsend, J. R., Stout, J. R., Morton, A. B., et al. (2013). Excess Post-Exercise Oxygen Consumption (Epoc) Following Multiple Effort Sprint and Moderate Aerobic Exercise. Faculty Bibliography 2010s. 4767.
Applied Exercise Science 