A cooling-off period should follow any workout. Cooling off, or more accurately tapering off, consists of slowing down to a crawl but keeping moving. After a vigorous game of squash, you might leisurely yet purposefully mosey around the court for two or three laps at a decelerating dawdle. There are sound reasons for a relaxed dawdle.
While you are actively engaged in exercise your heart is pumping out blood much faster in order to keep the muscles supplied with oxygen and nutrient. During this exercise the blood, having left the muscles, arrives at the other end of the muscles, or the veins. Blood reaches the muscles due to the forceful pumping action of the heart. But there is no such mechanism to effect return of the blood to the heart.
Blood flow during workouts
Once blood passes across the muscles and into the veins, the main channels to the heart, some pumps must be found. Unlike the arteries the veins are thin-walled and almost devoid of muscle. They are easily compressible. When veins are filled with blood, the pressure of adjacent contracting muscles produces a ‘ ‘milking action” on the veins with the propulsion of blood toward the center of the body because veins have valves which direct blood flow to the heart.
If you abruptly end a workout, your heart for a while continues to send extra blood to the muscles. But because your muscles have suddenly stopped moving, there is no adequate means of sending blood back to the heart. Blood then pools in the muscles with inadequate blood left to nourish the other organs. Without enough blood to the brain, you might “pass out.” Perhaps you have seen U.S. Marines or Buckingham Palace guards keel over while at attention. This results from blood being sent to the legs which puddles there and has no round-trip ticket to the heart. With a large amount of blood thus sequestered in the legs, there is not enough to deliver an adequate amount of oxygen to the brain, and the man faints. By tapering off slowly, your muscles continue to milk blood from the extremities back into the main circulatory system.
Why you need to cool down after workouts
If your muscles are vigorously exercised and then suddenly allowed complete rest, you may just as suddenly experience cramps. Muscles, especially if untrained, should come to a halt gradually. Stiffness as well as cramps may be reduced by this maneuver.
Another practical consideration dictates a cooling-off period. If you jump into a tub immediately after a workout, you have not allowed sufficient time for the heat of energy to be radiated into the surrounding atmosphere. Your body temperature will remain above normal until this excess heat has been dissipated. The hot bath water prevents loss of heat. Thus when you step out of the tub you will continue to perspire profusely, necessitating another bath.
Cool down slowly in cold weather
On the other hand, should you cease exercising abruptly and do nothing for a few minutes, you may cool off too much and become chilled. The consequences of chilling after a heavy sweat are obviously identical to chilling after being soaked to the skin by cold rain. Be careful to avoid a chill during a workout. Perhaps you may substitute thirty minutes of shovelling out the driveway after a snowstorm for your usual workout. Or perhaps you are chopping wood on a blustery autumn day. Just as you have worked up a healthy lather, along comes your neighbor. Good chance to sit down and chew the fat! The customary inane banter of good fellowship fills the air and ten minutes later, amid of flurry of handshaking, back-patting, and “see-you-soons,” your neighbor departs, leaving you frozen stiff, shivering, and with chattering teeth.