Swimming is considered as the ideal form of exercising as the density of the human body is almost like to that of water, so the body is greatly supported by water and less stress is hence placed on joints and bones. Perhaps that is why swimming is often recommended as the rehabilitation exercise after injuries or for the disabled.

Resistance swimming is a type of swimming exercise and is recommended either for training purposes for holding the swimmers in place for stroke analysis or enabling swimming in the restricted space for athletic or therapeutic reasons. Resistance swimming could be done either against the water stream set in motion generally by self-contained mechanical device called the swimming machine or by holding the swimmer stationary with the help of some elastic attachments.

Swimming is basically the exercise of aerobic category as it takes longer exercising time, needs consistent supply of oxygen to the muscles, except for short race where the muscles work an aerobically. The aerobic exercises generally burn fat and help losing weight, but swimming has no such effects except while swimming in the cold water where body burns more food energy for maintaining the body temperature.

It is not yet convincing why swimming does not reduce weight considerably, yet it appear to have links with better heat conduction of water, for that several reasons are assumed. Water is believed to cool the body rapidly as compared to air and many researchers consider that then the body targets maintaining the stratum of fat under the skin for insulation. Swimming could be good for asthma sufferers.