The purpose if the cool down is to ease out of your workout. Reverse of the warm-up.
Ease out of your workout just as you eased into it. When you have finished a 20-30 minute workout
on a treadmill or stationary bike, your heart is jumping and your blood is pumping into those
worked muscles. Cooling down puts your body back to normal working conditions. If you rush off
after a intense cardiovascular workout and don't cool down, you risk fainting, nausea, and dizziness.
So take 5-10 minutes to cool down. Most cardiovascular equipment will guide you through a cool down.
If not, just simply drop down a few levels for a few minutes and continue down till you have cooled down
and your body temperature has decreased.