The physiological feel of exercise makes you feel tired and hot.
This Time line explains how your body reacts to when you exercise physically.
This shows that when you exercise your body must adjust to the your change in activity level.
A post about exercise explains the great effects from head to toe from when you exercise.
This shows how Exercise causes your muscles to act like electric motors.
This video comes from NOVA and describes the cause and effect of exercise on the human body and defines a measure used to gauge aerobic fitness