It is otherwise known as post-exercise oxygen consumption. It is the amount of oxygen your body utilizes in order to return it to pre-exercise condiiton. The more oxygen your body uses, the more calories you burn. After you exercise, your muscles have been broken down. Blood flow increases to bring oxygen and nutrients to those muscles to help repair them. This can last anywhere from four to 16 hours post exercise. During this time, more calories are being burned, thus metabolic rate is higher after you exercise for up to 16 hours.
Here is the scientific proof
Studies have shown that EPOC is most prevalent in weight training rather than cardiovascular exercise. The body is able to return to pre-exercise conditions faster after cardio. But when muscles break down it takes much longer to repair them. A study conducted in the American College of Sports Medicine on women reported that three hours after weight training exercise they were burning 13% more calories than they did when they were rested. At 16 hours after the workout they were still burning at a 4.2% higher rate.
What did they do?
Their workout consisted of 10 exercises, 5 sets of each exercise, and 15 repetitions per set. Let’s do the math. Let’s say at rest (no movement whatsoever) you burn an average of 1500 calories per day (63 calories per hour, average for a 150 pound women who is mostly sedentary). You do a vigorous weight training workout in the morning. For the next 3 hours, you are burning 14% more calories, for a new total of 72 calories an hour. Caloric rate of burn decreases over the next 16 hours, but it is still higher than before exercise. You can burn as much as an extra 200 calories a day! That’s not counting the calories you burned while working out! Now if you weigh more, or are male, or are active on a daily basis, those number all increase further.
So what does this mean for you?
It means, hit the weights! You will be burning more calories after weight training than if you were to not exercise at all. It means for almost a whole day, your metabolic rate is higher. If your goal is to lose weight, this is a good thing! Monitor your diet to ensure that you are in caloric deficit, and hit those weights to speed your metabolism for almost a whole day!
Osterberg, K. L.; Melby, C. L.
Effect of Strenuous Resistance Exercise on Metabolic Rate and Fat Oxidation in Young Women
Medicine and Science in Sports and Exercise: Journal of the American College of Sports Medicine