Swimming
Swimming is the method by which humans (or other animals) move themselves through water. Swimming is a popular recreational activity, particularly in hot countries and in areas with natural watercourses. Swimming is also a competitive sport. There are many health benefits of swimming, yet basic swimming skills and safety precautions are needed to participate in water activities.
History
Swimming has been known since prehistoric times. Drawings from the stone age were found in "the cave of swimmers" near Wadi Sora (or Sura) in the southwestern part of Egypt. Written references date back up to 2000 B.C., including Gilgamesh, the Iliad, the Odyssey, the Bible (Ezekiel 47:5, Acts 27:42, Isaiah 25:11), Beowulf, and other sagas. In 1538 Nicolas Wynman, German professor of languages, wrote the first swimming book "Colymbetes". Competitive swimming in Europe started around 1800, mostly using breaststroke. The front crawl, then called the trudgen was introduced in 1873 by John Arthur Trudgen, copying it from Native Americans.
Swimming was part of the first modern Olympic games in 1896 in Athens. In 1902 the trudgen was improved by Richard Cavill, using the flutter kick. In 1908, the world swimming association Federation Internationale de Natation (FINA) was formed. Butterfly was first a variant of Breaststroke, until it was accepted as a separate style in 1952.
Competitive swimming
Swimming with the goal to maximize performance, usually the speed of swimming. Competitive swimming became popular in the 19th century, and is an event at the Summer Olympic Games. The competitive swimming's governing body is FINA, and there are four swimming disciplines regulated by it, swum over different distances.
There are a few different categories for competitive swimming. Competetive swimming can begin for children as young as 6 years old. Swimmers also compete well into their later years in Master's competitions. The most common competitions are judged in various yard or meter-length categories; the amount of times actually traversed from one end of the pool to the other depends on its length and the distance of that "event". Swimming races are held in the summer Olympics.
Additionally, there are so called "iron-man" competitions where the distances are much greater. There are records for individuals that have swam such bodies of water as the English Channel.
Competitive swimming at world level is regulated by FINA[1] and consists of races in a man-made pool of either 50 meters or 25 meters in length. In the USA many swimming competitions are contested in pools that are 25 yards long.
Types of strokes
There are different types of repetitive motions, known as strokes, that can be used to swim: the backstroke; the breaststroke; the butterfly; the side-stroke, and "freestyle".
Backstroke
The backstroke is performed while floating in the water on one's back. The legs alternate in kicking motions providing propulsion while the arms rotate about the shoulder. The arm stroke is performed in such a way that the greatest amount of momentum provided in the water occurs when the arm breaks the surface when raised straight up, over the top of the head with the palm facing outward (9 o'clock) to a position where the arm "pulls" the swimmer along under the surface of the water at a perpendicular (6 o'clock) with the palm facing up, acting as a paddle. The stroke is continued as the arm is brought up to the surface, palm upward (3 o'clock) and completed as the arm is raised to another perpendicular (12 o'clock) ready for the next iterative stroke. Each arm performs this movement; the other arm beginning the stroke when the first arm breaks the surface of the water over the top of the head, providing a continuous movement. Throughout the entire stroke, the head and body remain in a line approximately parallel with the surface of the water. Backstroke places no symmetry restrictions, but swimmers must lay on their back at all times except during turns to perform the stroke. Backstroke is performed, in essence, as an inversion of the crawl — competitors swing their arms back over their shoulder, alternately, and pull through under the water to provide motive power, with a flutter kick. Events are held at distances of 50 m, 100 m, and 200 m. Events are also held in yards.
Freestyle
Freestyle is a stroke performed while floating face-down in the water. The legs alternate in kicking motion, while the arms alternate "reaching out" to pull the swimmer forward. The majority of the thrust occurs when the outstretched arm breaks the plane of the water, and with arm fully extended is moved from a 9 o'clock position to a 3 o'clock; similar to that of a boat oar. On the side of whichever arm is due for the next stroke, the swimmer turns his head to that opening and takes in a deep breath. As the hand reaches forward, the head returns face-down in the water and the cycle repeats on the opposite side. Again, like the backstroke, the head and torso should remain in a line approximately parallel with the surface of the water, except during the breathe cycle. Freestyle refers to "any style", and in competitive swimming places no restrictions on what action the competitors use, except during the freestyle portion of medley swimming. In practice, almost all freestyle events are swum using front crawl. Events are held at distances of 50 m, 100 m, 200 m, 400 m, 800 m and 1500 m. Events are also held in yards.
Breaststroke 
Breaststroke is a symmetrical swim stroke. It begins with both hands pressed together directly in front of the breast area of the chest, forcing the elbows off to the side outwards. The knees are also drawn in halfway to the abdomen. The very next motion is the pushing of the hands directly out in front of the swimmer, still placed together, extending the swimmer's position into a straight line. At this moment, the knees and legs begin to come down and separate to either side. The swimmer's face will begin to come down into the water. Once the arms are fully extended, they part ways with hands facing away from each other. Arms kept stiff, both arms are swung out in tandem until they are perpendicular with the body; the legs providing a powerful "kick" and ending up back together behind the swimmer. At this point the swimmer's face will return to above the surface of the water due to the bodily motions. To repeat, the hands are redrawn inward to the breast-area of the chest; the knees are brought in, and the cycle repeats. Note that the breath should occur when the swimmer's head is pushed up out of the water and the arms are perpendicular to the body. Breaststroke from which the butterfly stroke evolved, places the additional restriction that the swimmer's hands must be pushed forward together from the breast and that the elbows must remain under the water. It is the slowest stroke in competitive swimming. Events are held at distances of 50 m, 100 m, and 200 m. This stroke, as well as butterfly requires great shoulder strength. Events are also held in yards.
Butterfly
Butterfly is symmetrical and swum on the breast just like the breaststroke. The stroke begins with the hands stretched out and together. Both arms pull back together under the breast, frequently in a key hole pattern towards the hips. They then recover above the water simultaneously. Hands must remain at a horizontal level. The kick requires that both legs and feet move up and down vertically at the same time. The kick occurs twice during the arm pull, once at the beginning of the underwater pull and the second time just before the arms come out of the water. It is commonly called a dolphin kick because the lower half of the body moves up and down similar to a dolphin swimming. To finish a race, the swimmer must contact the end of the pool with both hands simulataneously though not necessarily horizontally. Butterfly events require that the swimmer's actions retain bilateral symmetry (the left side of the body has to do the same as the right). Events are held at distances of 50 m, 100 m, and 200 m. Events are also held in yards.
In addition to that there are a number of combination events in competitive swimming.
Relay, where a number of swimmers swim sequentially. Events are held at distances of 4×50 m freestyle (short 25 lane only), 4×100 m freestyle and 4×200 m freestyle.
Individual Medley, where one swimmer swims Butterfly, Backstroke, Breaststroke, and Freestyle in this order. Events are held at distances of 100 m (short 25 m lane only), 200 m, and 400 m.
Medley Relay, where four swimmer swim Backstroke, Breaststroke, Butterfly, and Freestyle in this order. Events are held at distances of 4×50 m medley (short 25 lane only) and 4×100 m medley.
Competitive swimming has traditionally been dominated by the United States, but recently that dominance has been challenged by Australia , where swimming is a hugely popular recreational activity, and participant and spectator sport. The success of Australian swimmers like Ian Thorpe and Kieren Perkins is reminiscent of Australia's previous golden age of swimming in the 1950s and 1960s, which saw the emergence of swimmers such as Shane Gould and Dawn Fraser.
There are also a number of other Competitive swimming performances, for example a long distance 5 kilometer open-water event, which became part of the Olympic program in 2000, or long distance swims across the English Channel, or circumnavigating Manhattan Island. The world record for the longest nonstop swim is held by Martin Strel for swimming 504km nonstop in 2001 in the Danube River. He also swam the Mississippi River in 2002 in 66+2days, a total of 3885km.
Swimming is also a crucial part of other sports, such as water polo, synchronized swimming, modern pentathlon and triathlon.
Swimming for exercise
Swimming is a good form of exercise. Because the density of the human body is approximately similar to water, the body is supported by the water and less stress is therefore placed on joints and bones. Furthermore, the resistance against movement depends heavily on the speed of the movement, allowing the fine tuning of the exercise according to ones ability. Therefore, swimming is frequently used as an exercise in rehabilitation after injuries or for the disabled.
Swimming is an aerobic exercise due to the relatively long exercise times, requiring a constant oxygen supply to the muscles, except for short sprints where the muscles work anaerobically. As with most aerobic exercise it is believed to reduce the harmful effects of stress. While aerobic exercises usually burn fat and help with losing weight, this effect is limited in swimming, even though being in cold water burns more food energy to maintain body temperature.
The reason that swimming does not significantly reduce weight is still poorly understood, but seems to be related to the better heat conduction of water. A number of reasons are suspected.
1) First, water cools the body much faster than air, and most researchers believe that subsequently the body aims to maintain a layer of fat under the skin for insulation.
2) Secondly, it is believed that appetite decreases as your body temperature increases, as for example during exercise. However, during swimming the body is cooled down almost instantly as the surrounding water is usually cooler than the body temperature, and some researchers believe that this may actually increase the appetite. This assumption is not yet proven by research.
3) Finally, some researchers also believe that the metabolism of the body increases at higher body temperature, burning more food energy. Again, during swimming the body is cooled down by the surrounding water, reducing the metabolism, and subsequently the amount of food energy burnt. This assumption is also not yet proven by research.
Swimming exercises almost all muscles in the body. Usually, the arms and upper body are exercised 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 of the arms. However, 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 aqua aerobics.
Swimming is also for rehabilitation after injuries.
Recreational swimming
The most common reason for swimming is probably recreation, where the swimmer enters the water merely for enjoyment. Many swimming styles are suitable for recreational swimming. Most recreational swimmers prefer a style that keeps their head out of the water and uses an underwater arm recovery, for example breaststroke, side stroke, or 'dog paddle', however, out-of-water recovery of freestyle or butterfly gives rise to better exploitation of the difference in viscosity of the two media (air and water). Butterfly, which consists of out-of-water recovery with even symmetry in body movements, is most suited to rough water swimming. For example, Vicky Keithy crossed the rough waters of Lake Ontario using butterfly. Much of recreational swimming takes place in pools, where the water is calm. Therefore freestyle (which does not work as well in rough water) is suitable. However, playing around in rough water is a common source of recreation, but is sometimes dangerous due to undertow or being smashed into rocks on the bottom of the lake. Swimming pools are popular venues for recreational swimming, as are beaches, lakes, swimming holes, creeks, rivers, and sometimes canals.
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 paying attention to the water conditions. Possible health risks range from lethal to minor inconveniences. Below is a list of these risks, ranging from potentially lethal to minor temporary inconveniences.
1) 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.
2) 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.
3) 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 during swimming repeatedly for long periods of time, as for example in the case of competitive swimmers, can face adverse effects on the lungs.
Chlorine also has a negative cosmetic effect on hair after repeated long exposure.
4) 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, nor is there a known case of pregnancy due to sperm transported through the water while swimming.
5) 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 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 water 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.
6) 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 wile 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.
7) 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.
Clothing
The desire or cultural demand of modesty together with the awkwardness or unsuitability of conventional clothing in the water led to the development of the swimsuit (and in Victorian times, the bathing machine).
Men's swimsuits tend to be trunks, surf or boardshorts, competition briefs, cut-offs, or jeans.
Women's swimsuits are generally either one-piece swimsuits of traditional or competitive style (such as the racerback) or bikinis. Also there is the monokini, in case the coverage of the breasts is neither required nor desired. However, special swimsuits for competitive swimming, designed to reduce skin drag, can resemble unitards.
Nude swimming is done:
a) at nudist areas
b) during nudist hours in some swimming pools
c) at (usually small) swimming pools in saunas
d) without being formally allowed, at quiet places and hours; also called skinny dipping
e) at private swimming pools and beaches, not visible for outsiders
