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Swimming is a water sport; we have to learn to make good movement with our legs and arms.
When we correctly movement have and when we can stay at the surface when we would,
swim become a pleasant and a relaxant sport.
Historically, swimming was always practice, the human, and many animals can swim. Maybe
not with our manners but they can stay and move at the surface.
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
There isn’t a rule in free swimming, but there are security rules.
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:

Drowning, inhalation of water arising from
o Adverse water conditions swamping or overwhelming the swimmer or causing water
inhalation.
o Actions of others pushing under water accidentally in play or intentionally.
o Exhaustion or unconsciousness.
o Incapacitation through shallow water blackout, heart attacks, carotid sinus syncope or stroke.

Adverse effects of immersion
o Secondary drowning, where inhaled salt water creates a foam in the lungs that restricts
breathing.
o Salt water aspiration syndrome.
o Thermal shock after jumping into water can cause the heart to stop.
o 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)

Exposure to chemicals
o Disinfectant Chlorine will increase the pH of the water, if uncorrected the raised pH may cause
eye or skin irritations [6].
o 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, particularly for
asthmatics. This problem may be resolved by using a pool with better ventilation, with an
outdoor pool having the best results.
o Chlorine also has a negative cosmetic effect after repeated long exposure, stripping brown hair
of all color, turning it very light blonde. Chlorine damages the structure of hair, turning it
"frizzy." Chlorine can dissolve copper which turns blonde hair green. Proper pool maintenance
can reduce the amount of copper in the water, while wetting the hair before entering a pool can
help reduce the absorption of copper.
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o


Chlorine will often remain on skin in an anhydrous form, even after several washings. The
chlorine becomes odorous once it is back in an aqueous solution (when salivated on, during a
shower, etc.)
Infection
o Water is an excellent environment for many bacteria, parasites, fungi and viruses affecting
humans depending on water quality.
o Skin infections from both swimming and shower rooms can cause athlete's foot (boat bug).
The easiest way to avoid this is to dry the space between the toes. [7]
o Microscopic parasites such as Cryptosporidium can be resistant to chlorine and can cause
diarrheal illness when swimmers swallow pool water.
o Ear infections, otitis media, (otitis externa).
o When chlorine levels are improperly balanced, severe health problems may result, such as
chronic bronchitis and asthma.
Swimmer's own actions
o Overuse injury; competitive butterfly stroke swimmers for example may develop some back
pain, including vertebral fractures in rare cases, and shoulder pain after long years of training,
breaststroke swimmers may develop knee pain, and hip pain, and freestyle and backstroke
swimmers may develop shoulder pain, commonly referred to as swimmer's shoulder (a form of
tendinitis).
o 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
o Currents, including tides and rivers can cause exhaustion, can pull swimmers away from
safety, or pull swimmers under water.
o Wind enhances waves and can blow a swimmer off course.
o Hypothermia, due to cold water, can cause rapid exhaustion and unconsciousness.
o 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.
o Propeller damage is a major cause of accidents, either by being run over by a boat or
entanglement on climbing into a boat.
o Collision with another swimmer, the pool walls, rocks or boats.
o Diving into a submerged object, or the bottom, often in turbid water.
o Snagging on underwater objects, particularly submerged branches or wrecks.
o Stepping on sharp objects such as broken glass.

Aquatic life
o Stings from jellyfish and some corals.
o Piercings caused by sea urchins, zebra mussels, stingrays
o Bites from sharks and other fish and snakes, and pinches from lobsters or crabs.
o Electrocution from electric rays and electric eels.
Organisations publish safety guidelines to help swimmers avoid these risks
Technique
The human body is 80% water and has a very similar density to water. While the lungs
are filled with the 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
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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:
Try to keep the legs straight. Dropped legs or a slanted torso dramatically increase drag.
The hand should be extended forward of the head as far as possible. This increases the
average length at the water-line, substantially increasing speed.
Recent research[citation needed] 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 waterline 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).
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