Swimming is one of the most popular forms of aerobic exercise, and it is an excellent activity for anyone who wishes to get fit and stay active. Swimming exercise uses more of the overall muscle mass of the body than almost any other form of exercise, and people get an upper-body workout and a lower-body workout, unlike running or biking or other activities like tennis, where you get a good workout in just the legs. In addition, as with most aerobic exercise it is believed to reduce the harmful effects of stress.

Overall, swimming is an excellent form of exercise. Because the density of the human body is approximately similar to that of water, the body is supported by the water and less stress is therefore placed on joints and bones. Since then the buoyancy of the water protects the joints, water exercise is a particularly good choice for people who are overweight or who are prevented from taking part in other activities because of injuries or other physical limitations. Therefore, swimming is frequently used as an exercise in rehabilitation after injuries or for the disabled. It's also safe for older people and pregnant women.

For most adults, the upper body is the weakest part of the body. Swimming exercises the arms and upper body more than the legs. In competitive swimming, excessive leg muscles can be seen as a disadvantage as they consume more oxygen, which would be needed for the muscles in the arms, although this depends on the swimming style. While breaststroke generates significant movement with the legs, front crawl propels the body mainly with the arms.

Sometimes the swimming consists of swimming laps using a conventional stroke, such as the front crawl; other forms can include different forms of exercise performed in the water, such as water aerobics. Specifically, swimming and other forms of water exercise, such as water aerobics, offer remarkable cardiovascular benefits and are one of the few forms of exercise that work out the entire body. Swimming is primarily an aerobic exercise due to the relatively long exercise time, requiring a constant oxygen supply to the muscles, except for short sprints where the muscles work anaerobically. Particularly, water aerobics put a lot less stress on the knee and hip joints than running or many other aerobic activities. If you put people in the water, they don't have that pounding and compression on those joints, so they're able to exercise much more pain free. Moreover, if the water is warm, water exercise is good for people with arthritis.

Swimming and water aerobics are excellent and popular forms of exercise for the elderly, so long as the primary focus for exercise is not to improve osteoporosis.