The most important muscle that changes due to training is the heart. During exercise the heart pumps blood containing oxygen, fluid and nutrients to the active muscles, blood flow then drains the metabolic waste products away.
The heart adapts to aerobic exercise so it can pump more blood per stroke. In trained athletes who exercise on a regular basis, cardiac output can be increase up to eight times resting output, compared to four times for an untrained person. This is brought about not only by an increased heart rate but by a training induced increase in stroke volume. This can be increased by up to 50 to 60 percent during exercise. This is brought about by increased force of contraction and a greater emptying of the heart chambers. The heart of an aerobically trained person often increases in size, mainly because of the enlargement of the left ventricle.
But if you train in a different way, by lifting weights your heart adapts in a different way. Your heart must generate more force with each beat, so the heart works under increase pressure, in response the wall of the left ventricle thickens(5)
The circulatory system also changes due to exercise, at rest 20 percent of blood flows to the muscles this changes to 88 at maximum exertion. This increased flow of blood increases the exchange of oxygen, the release of heat and the removal of metabolic waste. The nervous system helps with exercise dilating your blood vessels by secreting hormones. With exercise there systems act more efficiently and rapidly to redistribute blood.
The number of blood capillaries increase with exercise, whilst the blood becomes thinner so it flows more effectively through the capillaries. The total number of red blood cells stays the same or slightly increases. But more water and dissolved proteins are added to the plasma, to thin the blood. This results in a decrease of the concentration of red blood cells. This is known as pseudo anaemia. It is not true anaemia because the red blood count has not fallen (5).
Exercise also affects the muscles, when exercising oxygen consumption increases by up to 70 times above resting value. Capillary density also changes increasing by up to 40 percent, enabling more oxygen, nutrients and hormones to be delivered to the muscles. This increases the muscles ability to use oxygen and store glycogen which together produces energy. Strength training increases the size and strength of muscles fibres, both types of exercise enable us to produce more mitochondria. Muscle development is determined by your testosterone levels and by the amount and type of muscular work you do (5).
The maximum oxygen uptake (VO2max) decreases with age steadily after you reach 20. A slower rate of decline happens for those who participate in regular exercise, without a decline in fat-free body mass. Canada’s McMaster University recently investigated the effects of exercise on maximum oxygen consumption. Over a course of 7 weeks VO2max increased by about 9%. At the beginning of the training course exercise lasted for about 14 minutes, by the end they had increased to 30 minutes. Therefore higher oxygen consumption means a higher stamina (4).
From: McArdle, D. Katch, I. Katch, L. (2000) Essentials of Exercise Physiology (second edition). P565
Jumping and weight lifting exercise help to build bones, making them stronger and thicker. This is very important for women who have a high risk of developing osteoporosis - a thinning of the bones which make s them less stable and more likely to fracture – after menopause (6). Exercise is likely to benefit your joints rather than injure them. Studies done by Stanford University indicate runners over the age of 50 actually develop fewer musculoskeletal disabilities than non-runners of the same age, these people also weighed less and took fewer medication (5).
Regular exercise contributes to “good health”, and a lifestyle of fitness could increase health benefits later in life. Those who exercise regularly could decrease their death rate by a half (4).
Exercise also reduces the risk of disease; experts of the American Heart Association say that “in activity is a major risk factor for heart disease.” New research has proved that exercise does more than just prevent heart disease; exercise can also decrease the odds of surviving a heart attack and preventing a second one (5).
Lastly exercise also effects you psychologically, if you begin to exercise regularly, your body goes through many physiological and neuromuscular changes. Naturally the change will be different for different type of intensity and frequency duration as well as people due to genetic differences (5). Studies done by Colorado University suggest that physiological responses to stress are moderated by regular exercise. If you exercise regularly you are less likely to feel sick after stressful situations. Exercising produces less neural activity during stressful periods. This was determined by the amount of Fos protein present in the pre-frontal cortex (3). Exercise affects the intelligence of the human mind, changing our ability to learn and to solve difficult problems. Physical activity can improve some of your mental abilities helping you absorb information a respond quicker and more tactfully. A well exercised mind can complete tasks using less energy (1).
Negative affects
“If the Government is propagating healthy exercise for everyone, the message must be taken in the context that some people will take health advice to an extreme.” Excessive exercise can damage your health, backs and neck can get strained, knees damaged, ankles twisted, there are disease waiting to be caught by enthusiasts, from conjunctivitis to legionnella. Medical specialists want the emphasis on quality not quantity (2).
When training the body expands the volume of the blood. This therefore allows more efficient diffusion of blood. This means there is a relative dilution of red blood cells in the plasma. Your blood count is lower causing a form of anaemia (psuedo) (5).
Molecules of iron are needed to make part of a protein called haemoglobin. Without an adequate mount of iron your body will become unable to make new red blood cells. Heavy exercise may increase your need for iron by up to another 1 to 2 milligrams a day (5).
Exercise is sometimes called a positive addiction, but even these can have there dark sides. Excessive exercise could lead to injuries or complicated eating disorders. People who suffer from over exercising have trouble distinguishing between pushing their limits and overstepping the mark. Many psychologists believe that people suffering with the addiction can become addicted to exercise rather than alcohol or drugs. People continue to exercise despite injuries, the lack of a social life, or underachieving academically. Addicts often set impossible tasks and often feel failure when these targets are not meet. Not all people who over train are exercise addicts, some people wrongly believe that more is better. These people haven’t realised the limitations of their own bodies. Many people don not realise that it is actually natural and most importantly healthy to have body fat, especially within the female anatomy where it is essential to the reproductive and immune system functioning. If body mass decreases drastically enough the bodies metabolism can be seriously upset, and the immune system can be weakened. Another possible result is amenorrhoea-an abnormal interruption of menstruation- research done by Barbara Drinkwater Ph.D. has concluded that
exercise-associated amenorrhoea is linked with a decrease in bone mass (5)
Conclusion
Therefore I conclude that exercise has many positive benefits like prolonging life, making you feel a better person, physically and psychologically. Helping you achieve the your goals in life. But exercise can only be done in the right quantity depending on a particular person. Excessive exercise can lead to mental instability and physical injuries. Quality exercise not the quantity of exercise is important, don’t let it take over your life.
Bibliography
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Bird, Ph. D. P. J. (1993) Exercise Effects on Intelligence. http://www.hhp.ufl.edu/keepingfit/Article/intelligence.HTM
- Dobson, R. (1998) Health: Warning: exercise can damage your health. Guardian Article 10.
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Flesnar, M. (2000) Science Journal studies. CU Studies- Exercise protects body against negative effects of stress from brain to cell.
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Katch, I. Katch, L. McArdle, D. (2000) Essentials of Exercise Physiology (second edition). Lippincott williams & Wilkins. Maryland. pg 568-570.
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Plough, L. (1999) Benefits of Exercise. http://www.sportsci.org
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Skyes, J. B. (1982) The Concise Oxford Dictionary. H. W. Fowler. Oxford
