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This article concentrates on human swimming. For other species, see Ability to swim.
Swimming is movement by humans or animals in water, usually without artificial assistance.
Additional recommended knowledge
Drawings from the Stone Age were found in "the cave of swimmers" near Sura, dating back to 2000 B.C. In 1538 Nicolas Wynman, German professor of languages, wrote the first swimming book. Competitive swimming in Europe started around 1800, mostly using breaststroke. The front crawl, then called the trudgen (now known predominantly as the "front crawl" or "freestyle") was introduced in 1873 by John Arthur Trudgen, copying it from Native Americans.
Swimming was part of the first modern 1896 Summer Olympics games in Athens. In 1900 backstroke was included as an Olympic Event. In 1908, the world swimming association Federation Internationale de Natation was formed. Butterfly was first a variant of breaststroke, until it was accepted as a separate style in 1952.
The human body is 80% water and has a very similar density to water. While the lungs are filled with air, the body is slightly less dense than the surrounding water, and there is a net upward force on the body. Thus staying afloat requires only a slight propelling of water downward relative to the body, and transverse motion only a slight propelling of water in a direction opposite to the direction of intended motion. Propelling is accomplished by using the hands and forearms as paddles, and by kicking the legs and feet to push water away from the body (though kicking accounts for relatively little thrust). Since salt water (e.g. the ocean) is denser than fresh water (e.g. most swimming pools), less effort is required to stay afloat in salt water than in fresh water.
Swimming styles have been developed based on the following principles:
Recent research has shown that hand force applied to the water is generated by the rotation of the hips, and not by the muscles of the arm. The muscles that pull the arm through the water are attached within one inch of the top of the arm. With a 21" arm, the lever ratio is 1:20, which means that a 100 lbs. of pull by the shoulder muscles produces only 5 lbs. of force at the hand as it pushes back against the water. The torque generated by the larger, stronger hip muscles, on the other hand, whips the hands through the water, much like golfers or batters whip their clubs and bats through the air with a fast turn of the hips. Elite swimmers who were able to make modest increases in the acceleration of their hips doubled their peak hand force output.
The time spent on the side should be maximized so the shoulders do not break the water-line and do not produce bow waves. This reduces the frontal cross-section, reducing drag further, and also increasing the ratio between the body's water-line-length and width. Similar improvements are possible by orienting the narrowest direction of head, hands, legs and arms into the water. The torso is by far the most critical. The motion of the hand, arm, and leg from the back to the front should be in the air for as much time during the recovery stroke as possible, and in the water, oriented as hydrodynamically as possible, because the returning appendage has to move at least twice as fast as the swimmer, and in the water generates eight times the drag (which increases with the cube of the speed) of an equal amount of torso frontal area. Rotating the shoulders also adds power to the pull by using abdominal muscles to help pull the arm through the water.
The basic "catch" of the water is not nearly as critical as the above items. Most swimmers simply grab water with their hand flat, or the fingers slightly spread, and then draw it smoothly down their body. None of the above techniques require improved strength. With strength training, the hands and feet can be extended further into the water, gaining more propulsion. For beginners, increased strength brings only small improvements if the above strategies (minimising drag and lengthening water-line) are not optimal.
Another technique that can help an athlete swim at a higher performance level is proper breathing techniques. Breathing correctly can make the swimmer swim faster and with less fatigue. Competitive swimmers take in one breath and gradually let it out over three to four strokes. As the race progresses and the swimmer becomes tired, less oxygen from those breaths reach the muscles. It is possible to teach the body to run on less than normal levels of oxygen. Take a deep breath at one side of a pool, submerge fully, and kick like a dolphin. Try crossing the pool with one breath, and then extend the distance. Another way to practice endurance is by taking a breath and letting it out over six strokes (while freestyle swimming).
Skeletal animation and computational fluid dynamics allow simulation of swimmers. This allows the forces on joints and muscles to be measured, and, if multiple simulations are employed, to compare different styles or individuals. By means of computer graphics or motion capture the simulation can be compared to real swimmers., 
The goal of competitive swimming is to be the fastest to swim a given distance. Competitive swimming became popular in the nineteenth century, and comprises 34 individual events - 17 male events and 17 female events. Swimming is a popular event at the Summer Olympic Games, where male and female athletes compete in 13 of the recognized events each. Olympic events are held in a 50 meter pool. Competitive swimming's international governing body is FINA (Fédération Internationale de Natation), the International Swimming Federation.
The four competitive strokes are the butterfly, backstroke, breaststroke, and freestyle (front crawl). While "freestyle" and "front crawl" are often used interchangeably, freestyle is the more common name and is used in most all club-swimming or international competitions. A swimmer may actually swim any stroke or combination of strokes in a freestyle race. Swimmers generally choose to swim front crawl in a freestyle event since it is typically the fastest stroke.
These strokes can be swum individually or together in an individual medley (IM). The IM order is: 1) butterfly, 2) backstroke, 3) breaststroke, and 4) freestyle. There are two types of relays: medley and freestyle. The medley relay order is: 1) backstroke, 2) breaststroke, 3) butterfly, and 4) freestyle. Each of the four swimmers in the relay swims a predetermined distance, dependent on the overall length of the relay. The three relay lengths are 200 meters or yards, 400 meters or yards, and 800 meters or yards (which is only swum freestyle). In a 50 meter pool, each swimmer swims one length for the 200 relay, two lengths for the 400 relay, and four lengths for the 800 relay. In a 25 meter or yard pool, each swimmer swims two lengths for the 200 relay, four lengths for the 400 relay, and eight lengths for the 800 relay.There have also been 100 yard relays that have been done by 8 and under swimmers, but is very rare except in summer recreation leagues. Many full-size competition pools in the United States have a length of 50 meters and a width of 25 yards (the Olympic pool size, allowing both short course (25 m or 25 yd pool) and long course (50 m pool) races to be held.
There are several types of judges: a starter sets off the swimmers; turn judges check that the swimmers' turns are within rules; stroke judges check the swimmers' strokes; time keepers time the swims; and the referee checks that everything is running smoothly. If an official catches a swimmer breaking a rule concerning the stroke he or she is swimming, that swimmer is said to be disqualified (commonly referred to as "DQ'd") and the swim is not considered valid, and therefore their time will not count.
In the United States and the United Kingdom, communities may sponsor competitive swimming leagues for children and teenagers, made up of swim teams. These leagues for the most part adhere to recognized swimming rules, swim the standard strokes, but swim shorter lengths as events in swim meets. These leagues are usually active in the warmer months, and are not directly associated with a national or world swim organization. However, swimmers who begin their competitive swimming experience on such a local swim team may go on to join a nationally-governed team.
In Australia such competition is usually conducted under the auspices of a club affiliated with the State Association which in turn is affiliated with Swimming Australia, the FINA accredited body. This provides a direct pathway to top level competition for those capable of taking it while still providing a more relaxed environment for those whose main intent is to have fun swimming competitively.
The most common purpose for swimming is recreation. Recreational swimming is considered by many a good way to relax, while enjoying a good full-body workout. Several swimming styles are suitable for recreational swimming; most recreational swimmers prefer a style that keeps their head out of the water and has an underwater arm recovery. Breaststroke, side stroke, and dog paddle, are the most common strokes utilized in recreational swimming, but the out-of-water arm recovery of freestyle or butterfly gives rise to better exploitation of the difference in resistance between air and water.
The butterfly stroke, which consists of out-of-water recovery with even symmetry in body movements, is most suited to rough water swimming. For example, in a record-setting example of endurance swimming, Vicki Keith crossed the rough waters of Lake Ontario using butterfly. Most recreational swimming takes place in pools, and calm natural waters (sea, lakes, rivers). Therefore freestyle (which does not work as well in rough water) is suitable.
Some occupations require the workers to swim. For example, abalone divers or pearl divers swim and dive to obtain an economic benefit, as do spear fishermen.
Swimming is used to rescue other swimmers in distress. There are a number of specialized swimming styles specially for rescue purposes (see List of swimming styles). Such techniques are studied by lifeguards or members of the Coast Guard. The training of these techniques has also evolved into competitions such as surf lifesaving.
Swimming is also used in marine biology to observe plants and animals in their natural habitat. Other sciences use swimming, for example Konrad Lorenz swam with geese as part of his studies of animal behavior.
Swimming also has military purposes. Military swimming is usually done by special forces, such as Navy SEALS. Swimming is used to approach a location, gather intelligence, sabotage or combat, and to depart a location. This may also include airborne insertion into water or exiting a submarine while it's submerged.
Swimming has become a professional sport as well. Companies such as Speedo, TYR Sports and Nike sponsor swimmers who are at the international level. Cash awards are also given at many of the major competitions for breaking records.
Swimming for exercise
Swimming is an excellent form of exercise. Because the density of the human body is very similar to that of water, the body is supported by the water and less stress is therefore placed on joints and bones. Therefore, swimming is frequently used as an exercise in rehabilitation after injuries or for those with disabilities.
Resistance swimming is one form of swimming exercise. It is done either for training purposes, to hold the swimmer in place for stroke analysis, or to enable swimming in a confined space for athletic or therapeutic reasons. Resistance swimming can be done either against a stream of moving water (often termed a swimming machine) or by holding the swimmer stationary with elastic attachments.
Swimming is primarily an aerobic exercise due to the long exercise time, 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. Swimming can improve posture and develop a strong lean physique, called, logically, a "swimmer's build": lean and spare throughout, with wide shoulders and a smaller lower body.
The risks of swimming
Swimming is a healthy activity and enjoys a low risk of injury compared with many other sports. Nevertheless there are some health risks with swimming, including the following:
Children are often given formal swimming lessons, which serve to develop swimming technique and confidence. Children generally do not swim independently until 4 years of age.
In Sweden, Denmark, Norway and Finland, the curriculum for the fifth grade states that all children should learn how to swim as well as how to handle emergencies near water. Most commonly, children are expected to be able to swim 200 metres (220 yards) – of which at least 50 metres (55 yards) on their back – after first falling into deep water and getting their head under water. Even though about 95 percent of Swedish school children know how to swim, drowning remains the third most common cause of death among children.
In both the Netherlands and Belgium swimming lessons under school time (schoolzwemmen, school swimming) are supported by the government. Most schools provide swimming lessons. There is a long tradition of swimming lessons in the Netherlands and Belgium, the Dutch translation for the breaststroke swimming style is even schoolslag (schoolstroke). The children learn with schoolswimming a variant of the breaststroke which is technically not entirely correct.
In many places, swimming lessons are provided by local swimming pools, both those run by the local authority and by private leisure companies. Many schools also include swimming lessons into their Physical Education curricula, provided either in the schools' own pool, or in the nearest public pool.
In the UK, the "Top-ups scheme" calls for school children who cannot swim by the age of 11 to receive intensive daily lessons. These children who have not reached Great Britain's National Curriculum standard of swimming 25 metres by the time they leave primary school will be given a half-hour lesson every day for two weeks during term-time. 
In Canada and Mexico there has been a call for swimming to be included in the public school curriculum. 
Men's swimsuits tend to be surf or boardshorts, competition briefs, or more improvised cut-off shorts. Almost always, the upper body is left uncovered. However, in the early part of the 20th century, it was illegal for men to be topless in the U.S.
Women's swimsuits are generally either one-piece swimsuits of traditional or competitive style (such as the racerback) or bikini. Another option would be a Tankini, more conservative than a bikini but still not a one-piece.
Bodyskins are special whole body swimsuits for competitive swimming, designed to reduce skin drag. The most popular type of bodyskin is Speedo's Fastskin series, which includes many models of the suit for both men and women.(See Competitive swimwear)
With the desire to go faster came the idea of specialized shorts, or swimsuits. Over the years, the swimsuit has become more and more advanced and today a suit creates less drag than human skin. The release of the Fastskin by speedo was big and led to more companies starting to create super fast suits.
|This article is licensed under the GNU Free Documentation License. It uses material from the Wikipedia article "Swimming". A list of authors is available in Wikipedia.|