HEALTH BENEFITS OF EXERCISE

class_exercise.jpgWhile debate still exists regarding the extent to which exercise decreases the risk factors associated with chronic diseases it has been shown to have definite positive effects on an individual’s lifestyle.
 
It increases quality of life by decreasing the incidence of cardiovascular disease, diabetes, osteoporosis and reducing anxiety and stress levels. It does this by manipulating many of the risk factors associated with these chronic diseases and therefore decreases the risk of their development.

Physical activity should therefore be an important part of everyday activities. It appears that aerobic types exercises such as walking and jogging can be used to manage and treat all of these diseases, however in the treatment of osteoporosis the more significant stresses, like those produced through rowing and weight lifting, should be placed on the skeleton.

Sendentary Behaviour

As technology has advanced and societies have become more westernised the incidence of sedentary behaviour has risen. This has also seen a rise in the incidence and mortality of chronic diseases like cardiovascular disease (50% of all deaths), Non-Insulin Dependant Diabetes (NIDDM - 10% of all deaths) and osteoporosis (20% of all deaths).

This has led to a significant increase in health care costs to the community, with these three chronic diseases thought to contribute to approximately $200,000,000 to the health care costs in the next decade.

In order to reverse these trends the National Heart Foundation has suggested that each individual participate in 30 minutes of accumulated exercise at a moderate intensity on all or most days of the week. While it is considered best to follow these recommendations, it has also been shown that for the sedentary, even slight changes in behaviour, such as a small rise in physical activity, decreases the risk of developing these chronic diseases.

Benefits

The benefits associated with physical activity include improvements in heart and lung fitness, general fitness, enhancement of weight loss and improved mental processes. In studies that have compared physically active subjects with their sedentary counterparts, it has been found that physically active subjects develop protective defences against all of the chronic diseases mentioned, as well as depression and anxiety. Throughout this paper the role that exercise plays in preventing or modifying many of the risk factors associated with these chronic diseases will be discussed.

Diabetes & Exercise

thumb_group_exercise.jpgDiabetes is characterised by an inability of skeletal muscle and liver tissue to take up glucose in response to insulin stimulation, resulting in a rise in insulin secretion by the pancreas, causing high insulin levels in the bloodstream. To treat this disease it is important to keep blood glucose levels within normal ranges. Exercise can be used to treat this disease.

Exercise is known to improve glucose control, i.e. muscle sensitivity to insulin, so that more glucose is taken up by muscles, less glucose is released from the liver and less insulin is produced by the pancreas. This has the effect of decreasing blood glucose levels, improving glucose control, and insulin response and insulin sensitivity.

Diabetics may also have some degree of obesity, high blood pressure, abnormal blood cholesterol profile and cardiovascular disease. Exercise can treat these abnormalities. It is known that exercise improves the blood cholesterol profile, decreases blood pressure and increases the amount of energy the body uses.

Coronary Artery Disease (CAD) and Exercise 

treadmill.jpgThis disease is characterised by a narrowing of the coronary arteries caused by an accumulation of fatty deposits. These fatty deposits are formed when high concentrations of cholesterol are seen in the bloodstream. The fatty deposits cause a decrease in oxygen supply to the tissues of the heart, which when starved of oxygen, may result in a heart attack.
Many studies have found an inverse relationship between physical activity and the development of CAD.

Regular physical activity improves the fitness levels of an individual. Improvements that decrease CAD risk are lower blood pressure, slower rise in heart rate during exercise, a more efficient heart, lower blood cholesterol levels and reduced blood glucose levels.
Exercise also leads to decreased blood clotting activity at rest, reduced red blood cell stickiness and increased insulin sensitivity. All of these factors have positive effects on the risk of CAD development.

Obesity and Exercise

The development of obesity occurs over many years and is a result of energy intake exceeding energy expenditure.

There are two main ways to produce weight loss. One is through reducing energy intake, so that there is a decrease in the total amount of energy that is consumed and therefore energy intake is less than energy expenditure.

Secondly physical activity can be used to increase energy expenditure so that it exceeds energy intake. Both of these process result in initial weight loss. With reduced energy intake alone however there is a decrease in the total amount of energy the body uses at rest and a loss of muscle. These factors contribute to a lower energy expenditure, which makes weight loss harder.
Physical activity acts in weight loss by counteracting the decrease in the amount of energy used at rest by the body and helping to maintain the balance between energy intake and energy expenditure.

Therefore a combination of energy intake and physical activity is considered the most effective for weight loss and weight maintenance. It has been found that aerobic exercises that use large muscle groups i.e. jogging, walking, swimming, cycling, are the most beneficial types of physical activity for weight loss.

Osteoporosis and Exercise

Osteoporosis is characterised by low bone density (BD) and low bone mineral content (BMC), both of which are lost through the ageing process. In many studies physical activity has been found to increase or maintain BD and BMC and thus prevent the development of osteoporosis. Exercises that stress the skeleton such as walking, jogging, stair climbing, rowing and weight lifting are thought to be sufficient enough for maintaining BD and BMC.

Psychological Benefits of Exercise

Exercise in the short term can lead to reduced stress levels (anxiety and tension), but isn't necessarily linked with reduced depression. A reduction in depression is only seen in mildly depressed patients and not normal individuals. Exercise has an effect on the 'psyche' of an individual by providing "time out" from distractions for the individual thereby acting as a diversion away from problems.

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