swim
Swimming refers to the floating of a body in a liquid and the movement of living things in water.
etymology
The old Germanic strong verb ( mhd. Swing , ahd. Swimman ) forms with its West Germanic instigation word inundate a phrase whose except Germanic relations have been clarified. The main meaning “moving in water” applies from the beginning, and originally only for humans. The meaning “flow into one another, become indistinct” comes up in the 18th century.
Swimming as a physical effect
When a body swims, this means that it remains on the surface of a liquid by displacing (with its submerged body) as much of it as it weighs ( Archimedean principle ). A floating body is therefore immersed so deep that the mass of the volume of liquid it displaces corresponds to its own mass. If this is the case, when the body is completely immersed in the liquid, then the body floats in the liquid without the need for a drive. This is used by fish and submarines . If a submerged body displaces less liquid than it weighs, it sinks to the bottom of the liquid.
Bodies that are designed as a sufficiently large hollow shape can, despite their greater specific weight, displace so much liquid that they remain in the floating state (as long as the liquid does not penetrate the cavity). For this reason, steel ships as well as concrete ships float , although steel and concrete have a significantly greater density than water.
Swimming as a form of transportation
principle
The principle of floating locomotion is that water is moved in one direction by suitable measures and the body slides in the opposite direction in response to this. To this end, different methods are used by living beings.
fishes
During the actual swimming movement, very slender swimmers, such as eels, perform a snaking motion, the curves of the trunk curvature always occurring in pairs. The wavelength of the movement is considerably shorter than the length of the body. They therefore do not have a caudal fin, as it is not needed. Other fish also wiggle, but the wavelength is usually longer than the body length, which requires a tail fin (the same applies to whales).
Contrary to previous ideas, the tail fin does not contribute to propulsion when swimming fast. It is used solely for direction control and steering. Propulsion is brought about solely by the alternating curvature of the rear part of the fuselage and the acceleration of the adjoining water that occurs on the convex side by reducing the local static pressure. There is only one force acting transversely to the direction of movement, which has to be compensated for by a compensating transverse force on the tail fin. The great advantage of this swimming movement is that no force has to be generated in the direction of flow.
With fast fish in turbulent flow areas, such as tuna and lamnid sharks, the movement occurs through the lateral curvature of the trunk. Therefore the large caudal fin is vertical.
More details in the article Fin , section Swimming ways of fish .
Other living things
In whales and dolphins, the spine is curved up and down, so the caudal fin of these marine mammals is horizontal. The movement of the spine in this direction is the same as that of mammals running on land. It is also very efficient and allows large whales, for example, to migrate over huge distances.
Squids, octopods, nautilus or cuttlefish use the recoil principle for propulsion. Seals use different techniques. Some seabirds, such as guillemots, also use their wings for propulsion underwater.
Sea turtles use their arms, which have been transformed into "wings", to move. With them, the force occurring when the air flows around the wings, similar to the lift force in birds, is used to generate propulsion. The wings generate this force hydrodynamically. In the case of vertebrates that do not live permanently in water, the propulsion is generated by the hydrodynamic resistance of the moving extremities. This form of movement is similar to paddling and rowing and is considerably less economical. Due to the shape of the shell of the sea turtles with the thickening on the upper side, a negative pressure is created when moving forward in the water above the upper side, while an overpressure is created on the lower side. This eliminates the need to carry your body weight, the fins only generate propulsion. That explains the ability to cover thousands of kilometers.
Humans also move their limbs in a way that uses resistance to generate force, such as the frog shown while swimming. However, this type of transportation is less efficient. Relatively efficient types of swimming movements have developed, which have become known primarily in swimming as swimming types or swimming techniques. Movement under water is cheaper than on the surface, because then the wave resistance does not occur. In any case, swimming on the surface requires that the condition of weight compensation is at least approximately fulfilled. A slight tendency to sink or sink can be compensated by directing the swimming movements not only horizontally, but also diagonally upwards against sinking.
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In extreme cases, a living being can “walk on water” with very fast leg movements, as the example of the Jesus Christ lizard shows.
Swimming in humans
distribution
Swimming is a popular pastime for people in natural waters such as seas, lakes and rivers, as well as swimming pools and swimming pools specially built for this purpose . Pleasure bathing and splashing around in the water are also part of swimming. Swimming must be learned, especially the mastery of individual swimming techniques. People who cannot swim are called non-swimmers .
In quarry ponds , swimming may be restricted or prohibited due to the dangers involved, bathing and swimming 100 meters above and below bridges is prohibited in Germany, and there is also a ban on swimming at weirs and at landing stages for passenger ships.
For some people, swimming is part of their job, such as lifeguards , combat swimmers, and divers . Swimming is also practiced as a competitive sport.
Elements of swimming
Laws of nature
The basics are Newton's laws (action and reaction), hydrodynamics , movement and training theory .
boost
The buoyancy depends on the body mass immersed in the water. The less it is immersed, the more the buoyancy must be through muscle power. The swimming beginner swims much easier if he also puts his head in the water. The human body has roughly the same density as water and feels almost weightless on the water surface (typical specific density of the body inhaled = 0.94 to 0.98 and exhaled = 1.01 to 1.07).
Body structure and fat distribution produce different lift distributions. People with a high percentage of body fat experience more buoyancy because the fat tissue has a density of around 0.94 kg / l, which is slightly below the value of water (1 kg / l). Some people also sink after they have inhaled fully, while others can float on the surface of the water without air in their lungs. See: Physics and Physiology of the Dead Man
Water resistance
The larger the area of the body opposite to the direction of movement and the greater the speed (resistance increases quadratically), the greater the resistance. The more “streamlined” the body, the lower the resistance. The water resistance is also dynamically dependent on the movement. Propulsion is created by using the greatest possible resistance (e.g. closed fingers when pulling the arm). In all movements in the opposite direction to the swimming direction, however, the resistance must be reduced through an optimal gliding position and optimal movement sequences (for example the overwater phase of the arm during crawl swimming ).
The water resistance also helps to strengthen the muscles, for example in water aerobics .
Propulsion
The propulsion takes place through muscle power. It is crucial that the maximum effort is made where it is most effective. The different swimming techniques have been optimized for thousands of years (for animals for millions of years), specifically trained in swimming lessons and improved in top-class sport with video analysis and movement studies.
Water position and sliding
The optimal water position reduces the water resistance. The body is as stretched as possible and as horizontal as possible in the water. The head is also always in the water. It is only twisted or lifted slightly for inhalation. Positioning in the water and sliding are taught first in swimming lessons after getting used to the water, for example, when the swimming students push off the edge of the pool with their feet and glide as far as possible with their arms out, their heads in the water, with their bodies stretched out.
coordination
The coordination of breathing and movement determines the safety of the beginner in the water. For advanced skiers, the coordination determines the endurance . A high level of performance is only possible if the oxygen supply and the exhalation of the stale air correspond to the biochemical processes in the muscles. The attainable speed also depends on the coordination.
History of swimming
Ancient testimonies
Swimming has been known since prehistoric times. The oldest evidence of swimming is a seal cylinder made of clay, dating from the 9th to 4th millennium BC. BC and was found in the cave of the swimmers near Wadi Sora in Egypt . Written evidence goes back to before 2000 BC. BC back. Early evidence is a biographical inscription from the First Intermediate Period of Ancient Egypt in Asyut , which reports that learning the art of swimming was part of the educational program of the children of the king and other high-ranking people.
Swimming instructors and aids such as rush belts , air-filled hoses or cork swimming belts are known from Greek and Roman times . Around 310 BC A Roman military swimming school is reported. The Romans swam in the Tiber or in fish ponds ( Piscinae ). During the imperial period (27 BC to 476 AD), larger swimming pools ( natationes ) were built within the thermal baths . When the Greeks or Romans met a particularly uneducated person in antiquity, they said of him that he “could neither read nor swim”.
Further evidence of swimming in antiquity can be found in the Gilgamesh epic , in the Iliad and the Odyssey , in Beowulf and in the Bible ( Ezekiel 47.5 EU , Acts 27.42 EU , Isaiah 25.11 EU ). In the Mishnah tract Qiddushin (29a) it is written that one of the tasks of the Jewish father towards his son is to teach him to swim.
Early swimming textbooks
Around 1500 children were taught to swim with the help of cow bladders . In 1538 the first known swimming textbook by Nikolaus Wynmann was published with the title Colymbetes sive de arte natandi dialogus ( The swimmer or a conversation about the art of swimming ). However, it could not have any effect, as it only described swimming, but not analyzed it and was only translated in 1866.
Far more important was Everard Digby , a professor of physics at Cambridge. His Latin work De arte natandi libri duo (1587) ( Two books on the art of swimming ) described a biomechanics of swimming and was considered the most progressive swimming book until the middle of the 19th century. Digby's second swimming book was soon translated into English (1595; 1658) and later into French (1696). The French translation by Thevenot was the basis of the swimming training of the French army and also served as a template for the translations into Dutch (1825), Spanish (1848) and Italian (1819).
The Little Textbook of Swimming Art for Self-Instruction (1798) by Johann Christoph Friedrich Guts Muths was a step backwards compared to Digby because, on the one hand, he founded systematic swimming training, on the other hand, he recommended dry exercises on land and exercises with the swimming belt in the water and did not participate as a teacher dealt with the physical characteristics. In the period that followed, dry runs on land were initially expanded in Germany.
Swimming lessons in the German Reich
From 1810 swimming lessons took place as mass lessons, initially in military swimming schools. In the German Reich , Kurt Wiessner was only able to break away from the mechanistic view of learning to swim around 1925 . The latter gave greater importance to getting used to the water and was an advocate of device-free swimming lessons. Instead of using counting commands, he let the students perform the movement sequences in the water from the very beginning. He is considered to be a pioneer of modern German swimming training, which begins with breaststroke.
swimming lessons
Healthy children can learn to swim from around the age of four or five, provided they are not afraid of the water. Swimming in physical education is also known as school swimming . The so-called baby swimming from the sixth week of life is based on an innate breathing protection and creeping reflex. These reflexes are lost in the third to sixth month of life, so that actual swimming ability has to be learned again later.
- Priority of compulsory schooling over the right of parents to bring up children
In school swimming, there is a conflict of values between religious freedom on the one hand and educational goals on the other.
In German-speaking countries there is no right to an exemption of Muslim children from mixed-sex swimming lessons. Both the German Federal Administrative Court and the Swiss Federal Court confirm this rule. In Austria, swimming lessons are a compulsory part of the curriculum, the form is left to the schools, so in Vienna there is a bath that is only open to Muslim women on one day, where swimming lessons take place.
A judgment by the Federal Administrative Court in Leipzig confirmed that the state educational mandate constitutionally justified this encroachment on the fundamental right of freedom of belief, since it was reasonable, e.g. B. to participate in burkini .
On January 10, 2017, the European Court of Human Rights in Strasbourg upheld the ruling passed by the Federal Supreme Court in 2012 that Muslim girls had to take part in swimming lessons for boys and girls in schools and that a fine imposed by the Basel Department of Education was correct after a Muslim father refused to send his two girls to swimming lessons.
Evolutionary biology
By some biologists were various evolutionary adaptations of anatomically modern humans ( Homo sapiens interpreted) to the effect that its ancestors in the course of the Incarnation a partially water-living have undergone phase. This so-called water monkey theory (also: water monkey hypothesis ) was never able to establish itself in specialist circles.
Transferred usage
The fact that you have no contact with the ground while swimming is also reflected in the use of language. The word is used to describe a feeling of insecurity (e.g. "getting into a swim while giving a presentation") or a vague impression (e.g. "the letters are blurred in front of the eyes"). Also, figuratively, you can swim in something other than water, e.g. B. in money when one has it in abundance.
There are many idioms associated with swimming.
literature
- John von Düffel: Swimming - a cultural history. Piper, Munich 2003, ISBN 3-492-23971-4 .
- Michael Hahn: Swimming. BLV Buchverlag, Munich 2004, ISBN 3-405-16684-5 .
Web links
Individual evidence
- ^ The dictionary of origin (= Der Duden in twelve volumes . Volume 7 ). 5th edition. Dudenverlag, Berlin 2014 ( p. 767 ). See also DWDS ( "swim" ) and Friedrich Kluge : Etymological dictionary of the German language . 7th edition. Trübner, Strasbourg 1910 ( p. 420 ).
- ↑ Bathing rules - badegewaesser.nrw.de , accessed on August 6, 2019.
- ↑ § 8.10 Bathing and swimming ban , ELWIS , as of May 31, 2014, accessed on August 6, 2019.
- ^ Contribution by Dietrich Wildung in: Lexikon der Ägyptologie Volume V , keyword swimming , Harrassowitz, Wiesbaden 1986, Sp. 765–766.
- ↑ Neither read nor swim. In: faz.net. October 29, 2004, accessed December 11, 2014 .
- ↑ Traditional texts on parenting (last accessed on November 22, 2012)
- ^ Bilz : The new naturopathic treatment (75th anniversary edition) .
- ^ Wolfgang Schneider: Folk culture and everyday life. In: Ulrich Wagner (Hrsg.): History of the city of Würzburg. 4 volumes, Volume I-III / 2, Theiss, Stuttgart 2001–2007, Volume 1 (2001): From the beginnings to the outbreak of the Peasants' War. ISBN 3-8062-1465-4 , pp. 491-514 and 661-665, here: pp. 504 and 664.
- ^ Arnd Krüger : Swimming. The change in attitude towards a form of physical exercise. In: Arnd Krüger , John McClelland: The beginnings of modern sport in the Renaissance. Arena, London 1984, ISBN 0-902175-45-9 , pp. 19-42.
- ↑ Swimming school Züri-Oberland: QQ question: "At what age should my child learn to swim?" , accessed on November 3, 2015, cf. on the fact that youth and sport offer swimming offers for children from 5 years: Guide for the implementation of Y + S swimming offers ( Memento of December 8, 2015 in the Internet Archive ) (from December 1, 2015), accessed on November 3, 2015.
- ↑ for example spiegel.de: Judgment on school sports: Nine-year-old Muslim must swim with them. (Higher Administrative Court Bremen, judgment (pdf; 49 kB) of June 13, 2012, file number: 1 B 99/12), spiegel.de of July 2, 2009: Headmasters of secondary schools can obtain the consent of the parents on the condition for the admission of the Make child . (OVG Münster)
- ↑ Federal court practice on the dispensation from swimming lessons in Switzerland. in: humanrights.ch , accessed on November 3, 2015.
- ↑ Provincial School Board for Lower Austria: Swimming lessons for Muslim girls / Joint swimming lessons for Muslim girls with boys. dated May 28, 2014, accessed November 3, 2015.
- ↑ Az .: 6 C 25.12, judgment of September 11, 2013.
- ↑ Judgment "2C 666/2011 (March 7, 2012)" of the Federal Court on relevancy.bger.ch.
- ↑ Faz.net: Muslim women must take swimming lessons , accessed on January 10, 2017
- ↑ Katharina Fontana: No Muslim special requests. European Court of Human Rights. Neue Zürcher Zeitung, January 10, 2017, accessed on January 10, 2017 .
- ^ JH Langdon: Umbrella hypotheses and parsimony in human evolution: a critique of the Aquatic Ape Hypothesis. In: Journal of Human Evolution. Volume 33, No. 4, 1997, pp. 479-494, ISSN 0047-2484 . doi: 10.1006 / jhev.1997.0146 . PMID 9361254 . (Review).
- ↑ discovermagazine.com of September 5, 2007: Stephen Ornes: Whatever Happened To… the Aquatic Ape Hypothesis? Here, too, it says literally: "the aquatic ape hypothesis never got much support from the scientific community."