Q: Is it true that you shouldn't lay down on a mat and stretch if we got our heart rates up very high beforehand? If it is true, then how long should we wait/cool down before we can stretch laying down on the mat?

A: I recommend cooling down after an exercise by simply walking or lighly jogging for a few minutes. In between weight-training sets, especially when working legs, I also recommend walking around and breathing deeply as opposed to sitting down for a couple of minutes before the next set.