EPOC - Excess post-exercise oxygen consumption

Let's take an example that you have just been out for a long run over your lunch break. You grab a quick cold shower, but as you are getting dressed you feel like you are still sweating and warm. Initially you might panic that you are just super unfit and it is taking forever for your heart rate to decelerate, but chances is are you in a state of excess post-exercise oxygen consumption (EPOC).

EPOC is also referred to by some as the after-burn effect, what is actually going on during this phase? We can basically think of this as the body returning itself to a resting state.

1. Lactate clearance - we (should) know by now that lactate is not the enemy when working at high intensity but we do get to a point when working anaerobically that we struggle to use up the lactate as energy. Once the intensity has come down we need to get this lactate level lower. This occurs during this period where we are consuming more oxygen than we would normally at rest and are exerting ourselves less than when active.
2. Restoration of muscle glycogen - Our body likes to use muscle glycogen when active to fuel the activity. Once we have signalled to the body that the activity is finished your body is looking to return to a state in which glycogen is stored in the muscles. It will do this in two ways, resynthesizing  muscle glycogen, and by gaining new muscle glycogen (that may be why you suddenly are craving those carbs!)
3. Muscular recovery - Beginning the muscular recovery process using protein to repair muscle tears. Getting stronger requires you to break down your muscles (in a controlled and progressive way) and building them back up again. This process also requires excess oxygen and can start happening right away. Consider ensuring that you have consumed some protein source before your workout (the timing of this is not quite as crucial as some may have you believe).
4. Restoring the body temperature back to normal. You body craves homeostasis (consistent body temperature, blood oxygen etc...) during EPOC your body is trying to get back to a state that is not at stress.

Next time you are feeling that warmth after a workout, know that your body is getting to work recovering itself but also it is burning a few extra calories in the process. Maybe next time leave your heart rate monitor on for the hour after your workout and see if you have a higher level of caloric burn.