Swimming is one of the few ways of getting exercise that improves your all-round fitness because it can boost strength, stamina and suppleness all at the same time. You can look at it as having all the cardiovascular benefits of running, but with some of the strength-building effects of weight training and some of the suppleness-promoting effects of dance classes.

Swimming uses all the major muscle groups, and is a demanding aerobic exercise that helps to keep your heart and lungs healthy. Swimming also helps to keep your joints flexible, especially in the neck, shoulders, hips and groin as your limbs and body move through the water.

Swimming is, generally, kinder to your body than land-based exercise because your natural buoyancy in water helps you avoid the jarring knocks that can cause injuries. In water you weigh about a tenth of your normal weight, and the range of motion for the less fit person is much wider, as the water supports the weight of your limbs.

Therefore, it's a good choice for people who want to exercise, but who might have problems with weight-bearing land-based activities. For example, swimming might suit those who have arthritis or back problems, weight problems or are pregnant.

An added bonus for those with lung conditions, such as asthma, is that the air round a swimming pool is usually very humid, which makes breathing more comfortable.