Lack of Exercise Effects
Research has found that a lack of physical activity plays a part in the development of several health problems, including lowered resistance to infection, weight problems and obesity, muscle atrophy, osteoporosis, hypertension (high blood pressure), heart disease, stroke and cancer.
Lowered resistance to infection
People who do not exercise may be more susceptible to infections than people who do. Lack of exercise appears to have a detrimental effect on the immune system, making people more vulnerable to viral infections such as the common cold. Also, when unfit people do become infected, the duration and severity of illness is likely to be longer and worse than in a fit person.
Weight problems and obesity
People who do not take regular exercise risk becoming obese, particularly if their diet is high in saturated fats. Even people who eat a relatively well-balanced diet can still develop weight problems if they lead a very sedentary lifestyle.
Obesity is associated with serious health problems, including diabetes and cardiovascular disease, and it can aggravate existing conditions such as osteoarthritis. Obese people may also suffer from low self-esteem and depression. People who are overweight may find it difficult to start exercising. This can lead to a vicious circle of inactivity causing weight gain, which in turn increases inactivity.
Training increases the size of muscle fibres (hypertrophy) and, conversely, lack of training decreases their size (atrophy). Atrophy may result from a period of prolonged illness, when the body has to use up protein reserves stored in the muscles. Muscle atrophy is also a common feature of old age. The result of muscle atrophy is a marked reduction in strength and an increase in fatigue and susceptibility to accidents.
Contrary to popular belief, older people can increase their muscle strength, even at quite advanced ages. One study showed that people around the age of 90 benefited greatly from an eight-week programme of leg-strengthening exercises: they could rise from a chair more easily, walk faster and, in some cases, were able to abandon walking aids.
Lack of Exercise and Osteoporosis
One of the main bone diseases to affect older people, mainly women, is osteoporosis. Osteoporosis is a degenerative bone disorder characterized by porous bones. It causes bones to become brittle and prone to fracture on minor impact. Post-menopausal women are particularly at risk of developing osteoporosis. Regular weight-bearing exercise, such as aerobics classes, jogging or weightlifting, helps to keep bones strong and can prevent the onset of osteoporosis or slow the bone mineral loss in those who have developed the disease.
An individual with high blood pressure in the main arteries when he is at rest is described as having hypertension. Although hypertension is usually symptomless, it is dangerous because it dramatically increases the risk of stroke and coronary artery disease. Inactivity is known to be a risk factor in the development of hypertension, and research has found that a person who takes regular exercise is approximately half as likely to die due to hypertension as his inactive counterpart. Exercise lowers blood pressure and also helps to preserve the elasticity of the blood vessels (blood vessels tend to become rigid with age and this forces blood pressure to rise).
Lack of Exercise and Heart disease
In 1993, the American Heart Association stated that inactivity was one of the risk factors involved in the development of coronary artery disease (CAD). CAD is one of the main causes of death in the Western world. It occurs when the arteries that supply blood to the heart become narrowed by fatty deposits known as atheroma. Heart attacks occur when blood flow is so restricted, that the heart can no longer function. Regular exercise can slow or halt this process. Research on Harvard University graduates has concluded that activity levels need to be maintained throughout life in order to significantly lower the risk of coronary artery disease.
When the blood supply to the brain is interrupted (usually by a clot) or blood leaks through the vessel walls into the brain, this is known as a stroke. The most common causes of strokes are hypertension and narrowing of the arteries: a sedentary lifestyle with little or no exercise increases the risk of both of these. Inactivity also decreases the body’s capacity for dissolving dangerous blood clots, which cause strokes if they reach the brain.
Cancer is a group of diseases in which the cells in a particular part of the body multiply without control. As the abnormal cancer cells proliferate they start to compete with normal cells for resources, such as nutrients. These abnormal growths or tumours develop on or inside the body, and impede its healthy functioning.
The causes of cancer have been the subject of extensive research and it is thought that a complex interaction of factors, including heredity, age, diet, living environment and exposure to pollutants, may be responsible.
The relationship between exercise and the risk of cancer is still being investigated, although evidence suggests that long-term physical activity may be associated with a decreased risk of certain types of cancer such as cancer of the colon. This may be because regular activity speeds up the passage of food through the intestines, meaning that the colon is exposed to potential carcinogens for a shorter length of time. Sedentary people may be up to three and a half times more likely to develop cancer of the colon than people who take regular exercise. Cancer of the colon is a common type of cancer in the West.