Swimming

Swimming is the method by which living creatures move themselves through water in a method not involving simply walking on the bottom. Swimming is a popular recreational activity and a competitive sport. There are many health benefits of swimming, but it also entails risks if basic precautions are not taken.

Health risks

Swimming is considered a sport with a low risk of injury. Nevertheless there are some health risks with swimming. Most lethal risks in swimming are due to the inability to swim. It is recommended to swim in an area supervised by lifeguards and to pay attention to the water conditions. Possible health risks, ranging from potentially lethal to minor temporary inconveniences, are listed below:

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• Drowning can cause injury or death.
• Drowning due to adverse water conditions which may force the body under water or force water into the body.
• Drowning due to negative buoyancy, for example due to being attached to items heavier than water, e.g. medieval armour or a concrete block around the feet, or being trapped in an item heavier than water, e.g. a sinking ship.
• Drowning due to outside influence, as for example being pushed under water by another person by accident or intentionally.
• Drowning can also be caused by the inability to swim due to exhaustion or unconsciousness or a combination thereof. Besides other health risks listed below this may be due to effects unrelated to swimming as for example heart attacks and other strokes.
• Risks due to the effect of water on the human body.
• Secondary drowning, where inhaled salt water in the lungs after a near drowning starts to create a foam in the lungs that restricts breathing.
• Thermal shock after jumping into water can cause the heart to stop.
• Spending time in the water can give a wrinkled skin on the fingers, palms of the hands, and the soles of the feet. This disappears quickly without any negative effect.
• Injuries may heal slower if submerged in water.
• Risks due to chemicals in the water.
• In chlorinated swimming pools the chlorine may burn in the eyes. This stops shortly after leaving the water. Other disinfection techniques using, for example, ozone can avoid this effect.
• Breathing small quantities of chlorine from the water surface whilst swimming for long periods of time may have an adverse effect on the lungs.
• Chlorine also has a negative cosmetic effect on hair after repeated long exposure.
• Risks due to bacteria, fungi and viruses in the water. Water is an excellent environment for many bacteria, which may affect humans. The risk and severity of infection vary with the water quality. A selection of more common infections related to swimming are:
• Swimming and showering can cause athlete's foot (boat bug). The easiest way to avoid this is drying the space between the toes after swimming.
• Swimming can cause ear infections in the ear canal (Otitis externa).
• Cases of Legionnaires' disease have been transmitted by improperly sterilized showers after swimming. Good swimming facilities heat the shower water to 60°C (140°F) once per week during closing time to disinfect the water system.
• There is no known case of transmission of AIDS through the water.
• There is no known case of pregnancy due to sperm transported through the water while swimming.
• Risks due to physical activity in the water specific to swimming.
• Competitive swimmers may have a health risk due to overuse. Butterfly swimmers for example may develop some back pain and shoulder pain after long years of training, breaststroke swimmers may develop knee pain, and front crawl and backstroke swimmers may develop shoulder pain.
• Long term swimmers may occasionally get some abnormal growth in the ear canal due to the frequent splashing of water in the ear canal.
• Shallow water blackout is a condition where holding the breath causes a sudden unconsciousness due to oxygen starvation (Asphyxia).
• Exhaustion due to long swims or bad physical shape can cause drowning.
• Risks due to water and weather conditions.
• An outdoor swimmer can be hit by lightning during a thunderstorm. Lightning will usually hit the highest point available, as for example the head of a swimmer on a flat water surface.
• Strong winds can cause waves and can blow a swimmer away from land.
• Hypothermia due to cold water can cause rapid exhaustion and unconsciousness depending on the water temperature and the body conditions.
• Currents, including tides and rivers can cause exhaustion and can move a swimmer away from safety or pull swimmers under water.
• Due to the reflections in the water, the effect of the sun is more severe than on land, causing sunburn. Furthermore, swimming is usually done while exposing most of the body to sunlight, especially some areas usually covered (around the rims of the bathing suit) or in the shade (the back of the knees). In the long term this may increase the risk of cancer and decrease the aesthetics of the skin.
• Risks due to other objects in the water.
• A collision with another swimmer or other object as for example the wall of a pool, rocks, and boats, especially the propellers thereof, may result in injuries. Severe injuries are possible after hitting an object while diving into the water. Injuries can also be caused by stepping on sharp objects, e.g. broken glass.
• Dangerous marine life can attack swimmers in self defense or for prey, often in combination with a poison.
• Marine life that sting, e.g. jellyfish and some corals.
• Marine life that pierce, e.g. sea urchins.
• Marine life that bites, e.g. sharks and other fish, snakes, or lobster and crabs.