Regular exercise makes the heart stronger and the lungs fitter, enabling the cardiovascular system to deliver more oxygen to the body with every heartbeat and the pulmonary system to increase the maximum amount of oxygen that the lungs can take in. Exercise lowers blood pressure, somewhat decreases the levels of total and low density lipoprotein (LDL) cholesterol (the bad cholesterol), and increases the level of high density lipoprotein (HDL) cholesterol (the good cholesterol) These beneficial effects in turn decrease the risk of heart attack, stroke, and coronary artery disease. In addition, colon cancer and some forms of diabetes are less likely to occur in people who exercise regularly.

Exercise makes muscles stronger, allowing people to do tasks that they otherwise might not be able to do or to do them more easily. Every physical task requires muscle strength and some degree of range of motion in joints. Regular exercise can improve both.

Exercising stretches muscles and joints, which in turn can increase flexibility and help prevent injuries. Weight-bearing exercise, such as brisk walking and weight training, strengthens bones and helps prevent osteoporosis. Exercise can improve function and reduce pain in people with osteoarthritis, although exercises that put undue strain on joints, such as jumping and running, may need to be avoided.

Did You Know... Most frail, elderly people benefit from exercise at least as much as younger people.

Exercise increases the body's level of endorphins, chemicals in the brain that reduce pain and induce a sense of well-being. Thus, exercise appears to help improve mood and energy levels and may even help relieve depression. Exercise may also help boost self-esteem by improving a person's overall health and appearance.

In addition to all its other benefits, regular exercise helps older people remain independent by improving functional ability and by preventing falls and fractures. It can strengthen the muscles of even the frailest older person living in a nursing or retirement home. It tends to increase appetite, reduce constipation, and promote sleep.

The benefits of exercise diminish within months after a person stops exercising. Heart strength, muscle strength, and the level of high density lipoprotein (HDL) cholesterol (the good cholesterol) decrease, whereas blood pressure and body fat increase. Even former athletes who stop exercising do not retain measurable long-term benefits. However, people who were physically active in the past regain fitness faster.

Athletic Heart Syndrome Athletic heart syndrome refers to the normal changes that the heart undergoes in people who regularly do strenuous aerobic exercise (for example, very well conditioned athletes) and, to a variable extent, in those who do extensive weight training. In a person with athletic heart syndrome, the heart is larger and its walls thicker than in a nonathlete. The chambers inside the heart get somewhat larger. This increase in size and thickening of walls allow the heart to pump substantially more blood per heartbeat without much increase in heart rate. The large volume of blood flowing through the heart results in a slower, stronger pulse (which can be felt at the wrist and elsewhere on the body) and sometimes in a heart murmur. These murmurs, which are specific sounds created as blood flows through the valves of the heart, are perfectly normal in an athlete and are not dangerous. The heartbeat of a person with athletic heart syndrome may be irregular at rest but becomes regular when exercise begins. Blood pressure is virtually the same as in any other healthy person. The enlarged heart can be seen on an echocardiogram and sometimes on a chest x-ray. A variety of changes are detectable on an electrocardiogram. These changes would be considered abnormal in a nonathlete but are perfectly normal in an athlete. When an athlete stops training, the athletic heart syndrome slowly disappears—that is, heart size and heart rate tend to return gradually to those of the nonathlete. Athletic heart syndrome is not thought to affect health in any way. The rare sudden deaths of athletes are usually due to underlying heart disease that was not previously detected rather than to any danger resulting from athletic heart syndrome.

Last full review/revision September 2007 by Brian D. Johnston