Swimming

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This article concentrates on human swimming. For other species, see Ability to swim.

Swimming is a technique that humans, and other animals, use to move through water using only movements of the body, for exercise, fun and competition. There are health benefits of swimming, but it also entails risks.

Contents

[edit] History

Swimming has been known since prehistoric humanoids. Drawings from the Stone Age were found in "the cave of swimmers" near Sura in the southwestern part of Egypt. Written references date back up 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 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 1902 the trudgen was improved by Richard Cavill, using the flutter kick. In 1908, the world swimming association Federation Internationale de Natation was formed. Butterfly stroke was first a variant of Breaststroke, until it was accepted as a separate style in 1952. Swimming is a good form of exercise. Because the density of the human body is approximately 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 water set in motion by a (usually) self-contained mechanical device (often termed a swimming machine) or by holding the swimmer stationary by means of elastic attachments.

Swimming is primarily an aerobic exercise due to the relatively 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. 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.

[edit] Technique

Main article: The ability to swim

The human body is composed primarily of water, and thus has a very similar density to water. Roughly, 70% of the body is water; while the lungs are filled with the air, the body is slightly less dense than the surrounding water, which exerts a buoyant force on it. 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. This propelling is accomplished by using the hands and forearms as paddles, and by kicking the legs to push water away from the body (though kicking accounts for relatively little overall).

A number of swimming styles have been developed based on the implementation of some or all of the following principles:
The torso and the legs should be kept as parallel as possible to the surface of the water. Dropped legs or a slanted torso dramatically increase drag. The hand should be extended forward of the head as much as possible. This increases the average length at the water-line, substantially increasing speed.

Recent research has shown that hand force applied to the water is really 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 because the torso is narrower front-to-back than side-to-side on most swimmers. 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 as possible, and in the water, oriented as perfectly 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.

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.

[edit] Competitive swimming

The goal of competitive swimming is to swim the fastest for a given distance. Competitive swimming became popular in the nineteenth century, and currently comprises 34 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. 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. 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. Many full-size competition pools in the United States have a length of 50 meters and a width of 25 yards, allowing both short course and long course races to be held.

In the United States and the United Kingdom many communities sponsor competitive swimming leagues (for children and young people 18 years of age and younger), made up of individual swim teams, which may range in size from a few dozen swimmers to several hundred swimmers. 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, some swimmers who begin their competitive swimming experience on such a local swim team go on to join a nationally-governed team, on their path to an Olympic berth later. Top american swimmers include Michael Phelps, Amanda Beard, Janet Evans, Cullen Jones, Katie Hoff, Jayme Cramer, Ryan Lochte, Aaron Piersol, Natalie Coughlin, Gary Hall Jr., Ian Crocker, and Brendon Hansen. Top Australian swimmers include Ian Thorpe, Grant Hacket and Libby Lenton.

Competitive swimmers use smaller more skin tight suits called jammers. These suits make the swimmer more aquadynamic. If the swimmer is in practice they might wear a drag suit over the jammer. This makes the swimmer slower in practice; they create "drag" so the swimmer gets a better workout. This is almost only done by competitive swimmers.

[edit] Recreational swimming

The most common reason for swimming is recreation, where the swimmer enters the water merely for enjoyment. Recreational swimming is considered by many a good way to relax, as well as providing 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 with 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.

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, where the water is calm. Therefore freestyle (which does not work as well in rough water) is suitable. Venues for recreational swimming are swimming pools, beaches, lakes, swimming holes, creeks, rivers, and sometimes canals.

[edit] Occupational swimming

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 studied to improve the performances of competitive swimmers. Swimming is also used in marine biology to observe plants and animals in their natural habitat. Other sciences may also use swimming, for example Konrad Lorenz swam with geese as part of his studies of animal behavior.

Swimming also has military purposes. A swimmer in the water or under the water can be difficult to detect, especially at night. 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 leaving a submerged submarine through a hatch or the torpedo tubes. Special equipment and techniques are also used to engage hostiles in and under water.

Swimming has more recently become a professional sport as well. Companies such as Speedo and Tyr Sports, Inc. sponsor swimmers just as Nike sponsors basketball players. Cash awards are also given at many of the major competitions for breaking records.

[edit] Swimming for exercise

Swimming is a good form of exercise. Because the density of the human body is approximately 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 water set in motion by a (usually) self-contained mechanical device (often termed a swimming machine) or by holding the swimmer stationary by means of elastic attachments.

Swimming is primarily an aerobic exercise due to the relatively 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. 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.

  • 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.
  • It is believed that appetite decreases as the 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.
  • Fast swimming requires a high level of effort, meaning glycogen rather than fat is burned. Prolonged exercise at lower intensity is better for fat-burning.
  • 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.
  • There is also a theory that people with a genetically higher body fat content tend to be more successful as swimmers since the increased buoyancy of the fat aids in floatation or the rounder shapes offer less resistance to the water.

It is surprising that, while swimming provides many health benefits, it offers almost zero benefit for bone density<ref>J Sports Med Phys Fitness., Regional and total body bone mineral density in elite collegiate male swimmers. 1999 Jun;39(2):154-9 (PMID 10399425)</ref>. Some additional form of exercise is required if maintaining bone density is of interest.

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 in the arms, although 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 water aerobics.

Swimming may be good for asthma sufferers.

Swimming uses all three energy production systems, which are the creatine phosphate system, anaerobic fermentation (also known as Lactic acid buildup system), and the aerobic system. These three systems produce energy in form of ATP to enable muscle use (among other body functions).

[edit] The risks of swimming

Image:Hanakapiai Beach Warning Sign Only.jpg
A sign warns hikers on the trail to Hanakapiai Beach.

Swimming is generally 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:

  • Drowning, inhalation arising from:
    • Adverse water conditions swamping or overwhelming the swimmer or causing water inhalation.
    • Negative buoyancy when attached to a heavy object or entrapment e.g. in a sinking ship.
    • Actions of others pushing under water accidentally in play or intentionally.
    • Exhaustion or unconsciousness.
    • Incapacitation through shallow water blackout, heart attacks, carotid sinus syncope or stroke.
  • Adverse effects of immersion
    • Secondary drowning, where inhaled salt water creates a foam in the lungs that restricts breathing.
    • Salt Water Aspiration Syndrome, SWAS.
    • Thermal shock after jumping into water can cause the heart to stop.
    • Exostosis which is an abnormal growth in the ear canal due to the frequent, long-term splashing of water into the ear canal. (Known as Surfers' ear or Swimmers' ear)
    • Injuries may heal more slowly if submerged in water.
  • Exposure to chemicals
    • Chlorine in the eyes; in chlorinated swimming pools the chlorine may burn the eyes, stopping shortly after leaving the water but may be persistent and serious. Other disinfection techniques using, for example, ozone can avoid this effect.
    • Chlorine inhalation; breathing small quantities of chlorine gas 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 after repeated long exposure, turning blonde hair green and stripping brown hair of all color, turning it very light blonde. Chlorine damages the structure of hair, turning it "frizzy."
  • Infection
    • Water is an excellent environment for many bacteria, parasites, fungi and viruses affecting humans depending on water quality.
    • Skin infections from both swimming and shower rooms can cause athlete's foot (boat bug). The easiest way to avoid this is drying the space between the toes after swimming.
    • Microscopic parasites such as Cryptosporidium can be resistant to chlorine and can cause diarrheal illness when swimmers swallow pool water.
    • Ear infections, otitis media, (otitis externa).
    • Legionnaires' disease may have been transmitted by showers after swimming. Heating the shower water to 60 °C (140 °F) once per week during closing time will disinfect the water system.
  • Swimmer's own actions
    • Overuse injury; competitive butterfly stroke 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, commonly referred to as swimmer's shoulder (a form of tendonitis).
    • Hyperventilation in a bid to extend underwater breath-hold times lowers blood carbon dioxide resulting in suppression of the urge to breathe and consequent loss of consciousness towards the end of the dive, see shallow water blackout for the mechanism.
  • Adverse water and weather conditions
    • Currents, including tides and rivers can cause exhaustion, move swimmers away from safety, or pull swimmers under water.
    • Wind enhances waves and can blow a swimmer off course.
    • Hypothermia, due to cold water, can cause rapid exhaustion and unconsciousness.
    • Sunburn severity can be increased by reflections in the water and the lack of clothing worn during swimming. Long-term exposure to the sun contributes to risk of skin cancer.
  • Objects in the water.
    • Propeller damage is a major cause of accidents, either by being run over by a boat or entanglement on climbing into a boat.
    • Collision with another swimmer, the pool walls, rocks or boats.
    • Diving into a submerged object, or the bottom, often in turbid water.
    • Snagging on underwater objects, particularly submerged branches or wrecks.
    • Stepping on sharp objects such as broken glass.
  • Legal pursuit
    • legislation relating to the above or (for skinny diving) modesty
    • infringement of ownership rights

[edit] Swimming lessons

Image:Girl with styrofoam swimming board.jpg
Swimming aids such as this styrofoam board can help children in learning to swim. They should only be used under adult supervision.

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.<ref name="canada">Template:Cite journal</ref>

In Sweden, Denmark and in 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, with the exact definition varying from school to school. 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.<ref name="simtillsyn">Template:Cite web</ref>

In the Netherlands swimming lessons under school time (schoolzwemmen, school swimming) are stimulated by the government. Most schools provide swimming lessons. There is a long tradition of swimming lessons in the Netherlands, the Dutch translation for the breaststroke swimming style is even schoolslag (school style).

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 publicly accessible pool.

Recently, in the UK, a new plan called 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. <ref name="topups_scheme">"Children unable to swim at 11 will be given top-up lessons", Telegraph Group Limited, 2006-06-14. Retrieved on 2006-07-12.</ref>

In Canada there has been a call for swimming to be included in the public school curriculum. <ref name="school_call">"Federal minister calls for school swim lessons", CTV, 2005-07-18. Retrieved on 2006-06-28.</ref>

[edit] Clothing

Main article: Swimsuit

Modesty 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, or more improvised cut-off shorts or even simply underwear. 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 USA.

Women's swimsuits are generally either one-piece swimsuits of traditional or competitive style (such as the racerback) or bikinis. Another option would be a Tankini, more conservative than a bikini but still not a one-piece. In some areas, women have the choice or make the choice of going topless.

Bodyskins are special whole body swimsuits for competitive swimming, designed to reduce skin drag. (See Competitive swimwear)

Image:Kids skinny dipping in India.jpg
Boys skinny dipping in a sacred tank of water in India.

Nude swimming is done:

[edit] References

<references/>

[edit] Bibliography

  • Maniscalco F., Il nuoto nel mondo greco romano, Naples 1993.
  • Mehl H., Antike Schwimmkunst, Munchen 1927.
  • Sprawson, Charles (2000). Haunts of the Black Masseur - The Swimmer as Hero. University of Minnesota Press. ISBN 0-8166-3539-0.
  • Tarpinian, Steve (1996). The Essential Swimmer. The Lyons Press. ISBN 1-55821-386-4.
  • Cox, Lynne (2005 by Harvest Books). Swimming to Antarctica: Tales of a Long-Distance Swimmer. 2005 by Harvest Books. ISBN 0-15-603130-2.

[edit] See also

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[edit] External links

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Swimming

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