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Discussion - During exercise, metabolism and heat production processes in the body increase significantly.

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Discussion During exercise, metabolism and heat production processes in the body increase significantly. Yet, body core temperature remains almost unchanged. The body balances the amount of heat produced during the exercise by losing the same amount of heat, to it's surroundings. More than 80% of the heat is lost through the skin's surface while less than 20 % is actually used to drive your muscles. Blood vessels near the surface of the skin dissipate heat. Therefore heat loss is effectively achieved by an increase in blood flow in the skin, where sweat is evaporated to cool your body. This process is called vasodilation/evaporation cooling Sweating is controlled by the temperature of the blood flowing to the part of the brain called the hypothalamus. When your temperature rises, you sweat more. During exercise, your heart beats rapidly to pump blood to bring oxygen to muscles and hot blood from muscles to the skin where heat can be dissipated. When you stop exercising, your heart immediately slows down, so less blood is pumped to your skin, and your temperature rises higher and you sweat more. If you are already overheated, this extra heat can cause you to pass out. This is particularly likely to happen when you exercise, particularly in hot weather, because food is converted to energy by a series of chemical reactions, each of which release heat. ...read more.


Ammonia is toxic to cells, it reduces the formation of glycogen, and it inhibits the energy cycle. Although we still do not know how much ammonia contributes to fatigue, we do know that the higher your blood ammonia, the poorer your performance. Blood flow through tissues is matched with the metabolic needs of the tissues. During exercise, blood flow through tissues is changed dramatically. Its rate of flow through exercising skeletal muscles can be 15 to 20 times greater than through resting muscles. The increased blood flow is the product of local, nervous, and hormonal regulatory mechanisms. When skeletal muscle is resting, only 20% to 25% of the capillaries are open, whereas during exercise 100% of the capillaries are open. Low oxygen tensions resulting from greatly increased muscular activity or the release of vasodilator substances such as lactic acid, carbon dioxide, and potassium ions causes dilation of precapillary sphincters. As a direct result, resistance to blood flow in skeletal muscle decreases. Therefore blood is forced into skeletal muscles. The movement of skeletal muscles that compresses veins in a cyclic fashion and the constriction of veins greatly increase the venous return to the heart. The resulting increase in the preload and increased sympathetic stimulation of heart result in elevated heart rate and stroke volume, which increases the cardiac output. ...read more.


The enlargement of the heart due to training allows it to pump the same cardiac output, with less beats. This is because the enlargement results in a larger stroke volume. Also, the subject's frequent exposure to aerobic workouts would enable the subject to recover quicker, and return to resting rate a lot quicker. Any illnesses/conditions that the subject may be experiencing Should a subject be suffering with an illness, as trivial as a minor cold, the body would still be required to work twice or three times as hard to fight off infection. The subjects resting and working heart rates would be significantly higher, the subjects temperature would be a lot higher. The subject would not recover as quickly following exercise and would not only find it hard to complete the moderate intensity section, but would not be able to competently complete the chest press section of the investigation. The results would be very misguiding and inaccurate. If one or more of the subjects have only just finished some sort of physical exertion prior to taking the test. Had a subject undergone an intense training session immediately prior to the investigation, the results would be very inaccurate. The training session would have a similar effect on the body as an infection would. It would require the body to work harder than usually required to perform such a task and it would also raise heart rate, blood pressure, and also lengthen the time taken for a subject to recover. Ben Davies N.D.S.S ...read more.

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