Swimming is the self-propulsion of a person through water, usually for recreation, sport, exercise, or survival. Swimmers achieve locomotion by coordinating limb and body movements to achieve a level of buoyancy and hydrodynamic thrust that results in directional motion. For example, they float to a greater or lesser extent, and move in a given direction by coordinating their forward thrusting actions, especially of their head and torso, with other actions such as stroking with their arms and kicking with their legs. Swimming is a whole body exercise that requires endurance, skill and efficient techniques to maximize speed and minimize energy consumption.
Swimming is consistently among the top public recreational activities, and in some countries, swimming lessons are a compulsory part of the educational curriculum. It offers numerous health benefits, such as strengthened cardiovascular health, muscle strength, and increased flexibility. It is suitable for people of all ages and fitness levels. As a formalized sport, swimming is featured in various local, national, and international competitions, including every modern Summer Olympics.
Swimming involves repeated motions known as strokes to propel the body forward. While the front crawl, also known as freestyle, is widely regarded as the fastest of the four main strokes, other strokes are practiced for special purposes, such as training and competition.
Swimming comes with many risks, mainly because of the aquatic environment where it takes place. For instance, swimmers may find themselves incapacitated by panic and exhaustion, both potential causes of death by drowning. Other dangers may arise from exposure to infection or hostile aquatic fauna. To minimize such eventualities, most facilities employ a lifeguard to keep alert for any signs of distress.
Swimmers often wear specialized swimwear, although depending on the area's culture, some swimmers may also swim nude or wear their day attire. In addition, a variety of equipment can be used to enhance the swimming experience or performance, including but not limited to the use of swimming goggles, floatation devices, swim fins, paddles, and snorkels.
Science
Swimming relies on the nearly neutral buoyancy of the human body. On average, the body has a relative density of 0.98 compared to water, which causes the body to float. However, buoyancy varies based on body composition, lung inflation, muscle and fat content, centre of gravity and the salinity of the water. Higher levels of body fat and saltier water both lower the relative density of the body and increase its buoyancy. Because they tend to have a lower centre of gravity and higher muscle content, human males find it more difficult to float or be buoyant. See also: Hydrostatic weighing.
Since the human body is less dense than water, water can support the body's weight during swimming. As a result, swimming is "low-impact" compared to land activities such as running. The density and viscosity of water also create resistance for objects moving through the water. Swimming strokes use this resistance to create propulsion, but this same resistance also generates drag on the body.
Hydrodynamics is important to stroke technique for swimming faster, and swimmers who want to swim faster or exhaust less try to reduce the drag of the body's motion through the water. To be more hydrodynamically effective, swimmers can either increase the power of their strokes or reduce water resistance. However, power must increase by a factor of three to achieve the same effect as reducing resistance. Efficient swimming by reducing water resistance involves a horizontal water position, rolling the body to reduce the breadth of the body in the water, and extending the arms as far as possible to reduce wave resistance.
Swimmers may opt to do some pre-swim exercises such as "arm swings", in which they rotate their arms like a windmill, to help loosen their joints and warm their muscles immediately before swimming. Outside the pool, swimmers may incorporate strength training exercises such as squats.Swimming Anatomy, Publisher: Human Kinetics, Year: 2010, , page: 147
A 2022 systematic review, published in Science & Sports journal, found that adding certain strength training exercises to traditional swimming training may improve both short and medium distance swimming performance. The authors concluded it would be "appropriate" to have strength sessions separated from swimming sessions within a training programme but cautioned against increasing the training volume too much, to avoid "greater fatigue" among swimmers.
Infant swimming
Human babies demonstrate an innate swimming or diving reflex from newborn until approximately ten months. Other mammals also demonstrate this phenomenon (see mammalian diving reflex). The diving response involves apnea, reflex bradycardia, and peripheral vasoconstriction; in other words, babies immersed in water spontaneously hold their breath, slow their heart rate, and reduce blood circulation to the extremities (fingers and toes). Because infants exhibit instinctual swimming behaviors, classes for babies about six months old are offered in many locations, and formal training is recommended to reinforce these abilities. This helps build muscle memory and makes strong swimmers from a young age.
Technique
Swimming can be undertaken using a wide range of styles, known as 'strokes,' and which are used for different purposes or to distinguish between classes in competitive swimming. Using a defined stroke for propulsion through the water is unnecessary, and untrained swimmers may use a 'doggy paddle' of arm and leg movements, similar to how four-legged animals swim.
Four main strokes are used in competition and recreational swimming: the front crawl (freestyle), breaststroke, backstroke, and butterfly.
In non-competitive swimming, there are some additional swimming strokes, including the sidestroke and survival backstroke. The sidestroke, toward the end of the 19th century, changed this pattern by raising one arm above the water first, then the other, and then each in turn. It is still used in lifesaving and recreational swimming. Survival backstroke is a modified form of backstroke designed to conserve energy and allow a swimmer to remain afloat for extended periods. It is generally performed while lying on the back, using a slow, controlled leg kick and alternating or simultaneous arm movements, with the face kept above the water. The stroke is primarily used in lifesaving, survival swimming and situations where conserving energy in the water is important.
Other strokes exist for particular reasons, such as training, school lessons, and rescue, and it is often possible to change strokes to avoid using parts of the body, either to separate specific body parts, such as swimming with only arms or legs to exercise them harder, or for amputees or those affected by paralysis.
History
Swimming has been recorded since prehistoric times, and the earliest records of swimming date back to Stone Age paintings from around 7,000 years ago. Written references date from 2000 BC. Some earliest references include the Epic of Gilgamesh, the Iliad, the Odyssey, the Bible (Ezekiel 47:5, Acts 27:42, Isaiah 25:11), Beowulf, and other sagas.
In 450 BC, Herodotus described a failed seaborne expedition of Mardonius with the words "…those who could not swim perished from that cause, others from the cold".
The coastal tribes living in the Low Countries were known as excellent swimmers by the Romans. Men and horses of the Batavi tribe could cross the Rhine without a loss of formation, according to Tacitus. Dio Cassius describes one surprise tactic employed by Aulus Plautius against the Celts at the Battle of the Medway:
The [British Celts] thought that Romans would not be able to cross it without a bridge, and consequently bivouacked in rather careless fashion on the opposite bank; but he sent across a detachment of [Batavii], who were accustomed to swim easily in full armour across the most turbulent streams. ... Thence the Britons retired to the river Thames at a point near where it empties into the ocean and at flood-tide forms a lake. This they easily crossed because they knew where the firm ground and the easy passages in this region were to be found, but the Romans in attempting to follow them were not so successful. However, the [Batavii] swam across again and some others got over by a bridge a little way up-stream, after which they assailed the barbarians from several sides at once and cut down many of them.
The Talmud, a compendium of Jewish law written compiled c. 500 CE, requires fathers to teach their son how to swim.
In 1538, Nikolaus Wynmann, a Swiss–German professor of languages, wrote the earliest known complete book about swimming, Colymbetes, sive de arte natandi dialogus et festivus et iucundus lectu (The Swimmer, or A Dialogue on the Art of Swimming and Joyful and Pleasant to Read).
The Birdman cult of Rapa Nui held an annual ritual competition to determine the Tangata manu, in which men swam one kilometer to and from an islet to collect the first sooty tern egg of the season. The ceremony was suppressed by Christian missionaries in the 1860s.
Competitive swimming in Europe started around 1800, mostly using the breaststroke, which started as the current breaststroke arms and the legs of the butterfly stroke. In 1873, John Arthur Trudgen introduced the trudgen to Western swimming competitions. Swimming was introduced as a competitional sporting event in the 1896 Summer Olympics in Athens, Greece.
The butterfly was developed in the 1930s and was considered a variant of the breaststroke until it was accepted as a separate style in 1953.
Purpose There are many reasons why people swim, from recreational intentions to swimming as a necessary part of a job or other activity. Swimming may also be used to rehabilitate injuries, especially various cardiovascular and muscle injuries. Professional opportunities in swimming range from competitive sports to coaching, lifeguarding, and working in aquatic therapy. Some may be gifted and choose to compete professionally and go on to claim fame.
Recreation
Many swimmers swim for recreation, with swimming consistently ranking as one of the physical activities people are most likely to participate in. Recreational swimming can also be used for exercise, relaxation, or rehabilitation.
Health