Your body naturally takes a while to fully recover from a workout. The harder you workout, the longer it takes for it to get back to its resting state. This resting state consists of your heart and breath rate, the amount of fuel your muscles contain for movement, as well as your metabolic rate. The interesting thing is, your body continues to expend energy during this long “cool down phase”.
This phase is called excess post-exercise oxygen consumption, and it can be a very effective way to lose weight, as well as tone up your muscles. excess post-exercise oxygen consumption has also been popularly referred to as oxygen debt, or the "afterburn" you feel post workout. Amazingly, you might not feel the effects 12 hours later, but they are still happening.
The fuel created in your body and stored in your muscles, is called adenosine triphosphate (ATP), and your muscles need it when you work out, as well as when you're just walking around and doing normal, everyday things. Your metabolism refers to how your body turns the nutrients you take in from the food you eat, into this muscle fuel. It can also be produced with oxygen.
This is why it's so important to do some warm up exercise at first, to bring in more oxygen, since your body will start producing ATP using oxygen for the first 5 to 8 minutes of the workout. Then, you can do your strength training, which will use the ATP your body created using nutrients.
Maintaining ATP can help you work out with strength training, which means EPOC will last longer, and you would have burned more calories in the long run. The following is a list of important things you should know about EPOC:
After your EPOC workout, oxygen is being used to...
... produce ATP and restore it to the muscles.
... take away the waste products of used-up ATP from the muscles.
... add oxygen back to the blood.
... repair muscle tissue that is damaged during exercise.
... bring your body temperature back to normal.
Exercise that uses more oxygen will burn more calories. Your body burns 5 calories to consume 1 liter of oxygen.
The most effective workout is circuit training and heavy resistance with short rest intervals. This requires more ATP, which heightens the EPOC effect. EPOC depends on the intensity of the workout, not the duration.
You won't get the effect of EPOC if you only do cardio, even if that exercise lasts for a long time. Your muscles aren't losing oxygen with cardio, in fact, they are gaining more oxygen.
Doing a high intensity strength training circuit before cardio will make the that more effective and will cause you to burn more calories during the cardio. It burns more calories, but only during the workout itself and not afterwards.