Cooling down after exercise is just as important as warming up. Just as the body was allowed to speed up gradually, it must be allowed to slow down gradually. The body is not analogous to an auto engine that can be turned on and off with the twist of a key. Like the warm-up, cool-down should last about 8 to 10 minutes. The first phase should consist of walking or some other light activities, and the second phase should consist of the same stretching exercises that were done during the warm-up.
Phase One: Light Activity
Five minutes of continuous light activity causes rhythmical muscle contractions that prevent the pooling of blood and help to move blood back to the heart for redistribution to the vital organs. This boost to circulation after exercise is essential to the cool-down.
Inactivity during this time forces the heart to compensate for the reduced volume of blood returning to it by maintaining a high pumping rate.
The recovery period following exercise represents a potential hazard if it is not approached properly. The exerciser runs the risk of dizziness, fainting, and perhaps more serious consequences associated with diminished blood flow, the most serious of which is sudden death. Although sudden death during or immediately after exercise is rare, it does occur, and the recovery period is a likely time for its occurrence.
The worst possible cool-down procedure after fast walking or jogging is to stop all activity and stand still. The blood vessels in the legs that were dilated during exercise remain that way for a time after exercise, so blood pools in the leg veins. The downward force of gravity impedes the return of blood from the legs to the heart. Dilation of the blood vessels plus the force of gravity reduces blood flow to the heart, which limits the amount available for the body’s various systems.
Because venous return of blood to the heart is reduced, the systolic blood pressure drops but the heart rate remains high. Systolic pressure is the pressure of the blood against the artery walls when the heart contracts. While the pressure is dropping, the hormone norepinephrine rises in the bloodstream. Norepinephrine constricts blood vessels and under normal circumstances raises the blood pressure.
Many authorities contend that the rise in norepinephrine after exercise is a safety mechanism in which the body reflexively attempts to maintain proper blood pressure. The stand-still posture after exercise, however, overcomes the action of norepinephrine so the pressure drops anyway. The rise in norepinephrine and drop in blood pressure coupled with a relatively high heart rate represent circulation that is out of kilter. This set of events can be a triggering mechanism for the onset of irregular heartbeats that can lead to sudden death.
The key to avoiding or at least substantially reducing the probability of sudden death after exercise is to keep moving. Walking at a moderate speed for 5 minutes will prevent blood from pooling in the legs because the contracting muscles squeeze the veins, sending more blood back to the heart. The rhythmic contractions of the leg muscles, called the “muscle pump,” act as a second heart, significantly assisting it to meet the body’s elevated circulatory demand. Another plus for light physical activity during cool-down is that it hastens the removal of lactic acid that has accumulated in the muscles.
Phase Two: Stretching Exercises
The second phase of cool-down calls for the same stretching exercises that were used during the warm-up. Exercisers probably will note that they tolerate stretching more comfortably after exercise, because of the increase in muscle temperature. Stretching at this time helps to prevent muscle soreness, and it provides the exerciser an opportunity to stretch the muscles that have been contracting repeatedly during the performance of exercise. This helps to maintain flexibility of the muscles and joint structures.
Bent-leg curl-ups or crunches should be added to the routine. Strong abdominal muscles are a postural aid because they provide support for the upper torso. Those who cannot do crunches correctly because of unused and weak abdominals should do modified sit-ups. Correct performance requires that the back be rounded as the participant sits up.
If you become nauseated after exercise, you should continue to walk. If you feel dizzy to the point that walking is not possible or advisable, lie down on your back. This position prevents the blood from pooling in your legs because the horizontal position nullifies the force of gravity. The feeling of nausea and subsequent vomiting when people exercise beyond their capacity is another of the body’s safety mechanisms. Vomiting kicks up the blood pressure toward normal, and within minutes you will begin to feel better.
