To become and stay fit, people need to exercise regularly. Exercise makes the heart stronger, enabling it to pump more blood with each heartbeat. The blood can then deliver more oxygen to the body, increasing the maximum amount of oxygen that the body can take in and use. This amount, called maximum oxygen uptake, can be measured to determine a person's fitness.
Exercise benefits the body in many other ways.
Stretching can increase flexibility. Weight-bearing exercise strengthens bones and helps prevent osteoporosis. Exercise can benefit people of any age, including older people. Recent studies show that exercise can strengthen the muscles of frail elderly people living in nursing homes. Older men who continue to train and compete in long-distance running races can maintain their maximum oxygen uptake.