Monday, April 30, 2007

Butterfly Stroke

The butterfly, (fly for short) is a swimming stroke swum on the breast, with both arms moving simultaneously. The butterfly kick was developed separately, and is also known as the "dolphin kick". While other styles like the breaststroke, front crawl, or backstroke can be swum easily even by beginners, the butterfly requires very good technique to be feasible. Many students consider it the most difficult style. It is the newest swimming style swum in competition, first swum around 1934.

The butterfly technique with the dolphin kick consists of synchronous arm movement with a synchronous leg kick. Good technique is crucial to swim this style effectively. The wave-like body movement is also very significant, as this is the key to easy synchronous over-water recovery and breathing.

In the initial position, the swimmer lies on the breast, the arms are stretched to the front, and the legs are extended to the back.

Arm Movement

The butterfly stroke has three major parts, the pull, the push, and the recovery. These can also be further subdivided. From the initial position, the arm movement starts very similarly to the breast stroke. At the beginning the hands sink a little bit down with the palms facing outwards and slightly down at shoulder width, then the hands move out to create a Y. This is called catching the water. The pull movement follows a semicircle with the elbow higher than the hand and the hand pointing towards the body center and downward. The semicircle ends in front of the chin, with the hands close together so the swimmer can form a triangle with the fingers.
The push pushes the palm backward through the water underneath the body at the beginning and at the side of the body at the end of the push. The swimmer only pushes the arms 1/3 of the way to the hips, making it easier to enter into the recover and making the recovery shorter and making the breathing window shorter. The movement increases speed throughout the pull/push phase until the hand is the fastest at the end of the push. This step is called the release and is crucial for the recovery. The speed at the end of the push is used to help with the recovery.

The recovery swings the arms sideways across the water surface to the front, with the elbows slightly higher than the hands and shoulders. The arms have to be swung forward fast in order to bring them to the front over the water. It is important not to enter the water too early, because this would generate extra resistance as the arms moved forward in the water against the swimming direction. A high elbow recovery, as in front crawl, would save more energy, yet the movement restrictions in the shoulders do not allow this easily, and due to the synchronized movement it is not possible to roll around the shoulders as in front crawl.

The arms enter the water with the thumbs first at shoulder width. A wider entry loses movement in the next pull phase, and a smaller entry, where the hands touch, wastes energy. After a brief rest the cycle repeats with the pull phase.

Leg Movement

The leg movement is similar to the leg movement in the front crawl, except the legs are synchronized with each other. The shoulders are brought above the surface by a strong up and medium down kick, and back below the surface by a strong down and medium up kick. A smooth undulation fuse the motion together.

The feet are pressed together to avoid loss of water-pressure. The feet are naturally pointing downwards, giving downwards thrust, moving up the feet and pressing down the head.
There is no actual stipulation in competitive butterfly rules that a swimmer make a fixed number of pulses in butterfly–the swimmer may kick as little or as much as he or she may wish. While competitive rules allow such a choice, the typical method of swimming butterfly is with two kicks.

As butterfly originated as a variant on breaststroke, it would be performed with a breaststroke or whip kick by some swimmers. While breaststroke was separated from butterfly in 1953, the breaststroke kick in butterfly was not officially outlawed until 2001.However a number of Masters swimmers were upset with the change since they came from a time when butterfly was usually swum with a breaststroke kick.FINA was then convinced to allow a breaststroke kick in Masters swimming. Given the option, most swimmers choose to use a dolphin kicking action, but there still is a small minority of swimmers who prefer the breaststroke kick, for recreational swimming and even for competition.


There is only a short window for breathing in the butterfly. If this window is missed, swimming becomes very difficult. Optimally, a butterfly swimmer synchronizes the taking of breaths with the undulation of the body to simplify the breathing process; doing this well requires some attention to butterfly stroke technique. The breathing process begins during the underwater "press" portion of the stroke. As the hands and forearms move underneath the chest, the body will naturally rise toward the surface of the water. With a minimum of effort, the swimmer can lift the head to break the surface fully. The swimmer breathes in through the mouth.

Experienced swimmers continue looking toward the bottom of the pool while they inhale to keep the body balanced and in a straight line. The head goes back in the water after the arms come out of the water as they are swinging forward over the surface of the water. If the head stays out too long, the recovery is hindered. The swimmer breathes out through mouth and nose till the next breath. Some swimmers, most notably Denis Pankratov, breathe to the side as in the front crawl, but their timing is otherwise the same. Such a style of breathing is quite uncommon though and generally discouraged by coaches.

Normally, a breath is taken every other stroke. This can be sustained over long distances. Oftentimes, breathing every stroke slows the swimmer down. (At a certain level, the stroke with a breath and the stroke without a breath become synonymous in their speed; therefore, very experienced competitors - such as Michael Phelps - may breath every stroke.) Other intervals of breathing practiced by elite swimmers include the "two up, one down" approach in which the swimmer breathes for two successive strokes and then keeps the head in the water on the next stroke, which is easier on the lungs. Swimmers with good lung capacity might also breathe every 3rd stroke during sprints or the finish. Some swimmers can even hold their breaths for an entire race (assuming that it is a short one).

Body Movement

Swimming the arms or the legs separately is difficult, and correct body movement is great for the arms and legs to use their full potential. The body moves in a wave-like fashion, controlled by the arm movement. As the hands go in, the hips go up, and the posterior breaks the water surface. During the push phase the head goes up and the hips are at their lowest position. In this style, the second pulse in the cycle is stronger than the first pulse, as the second pulse is more in flow with the body movement.


Butterfly uses the regular start for swimming. After the start a sliding phase follows under water, followed by dolphin kicks swum under water. Swimming under water reduces the drag from breaking the surface and is very economical. Rules allow for 15 m of underwater swimming, before the head must break the surface, and regular swimming begins.

Turn and Finish

During turns and during the finish, both hands must simultaneously touch the wall while the swimmer remains swimming face down. The swimmer touches the wall with both hands while bending the elbows slightly. The bent elbows allow the swimmer to push himself or herself away from the wall and turn sideways. One hand leaves the wall to be moved to the front underwater. At the same time the legs are pulled closer and moved underneath of the body towards the wall. The second hand leaves the wall to be moved to the front over water. It is commonly referred to as an "over/under turn" or an "open turn." The legs touch the wall and the hands are at the front. The swimmer sinks under water and lays on the breast, or nearly so. Then the swimmer pushes off the wall, keeping a streamline position with the hands to the front. Similar to the start, the swimmer is allowed to swim 15m underwater before the head must break the surface. Most swimmers dolphin kick after an initial gliding phase.
The finish requires the swimmer to touch the wall with both hands at the same time, in the same horizontal plane.

Sunday, April 29, 2007

The Risks of Swimming

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.
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)

Exposure to chemicals

Disinfectant Chlorine will increase the pH of the water, if uncorrected the raised pH may cause eye or skin irritations.

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.

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."

Chlorine will often remain on skin in an anhydrous form, even after several washings. The Chlorine becomes odourous once it is back in an aqueous solution (when salivated on, during a shower, etc.)


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 to dry the space between the toes.

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).

Unfortunately, when chlorine levels are improperly balanced, severe health problems may result, such as chronic bronchitis and asthma.

Swimmer's own actions

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).

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.

Dangerous aquatic life

Stings, jellyfish and some corals.

Piercings, sea urchins, zebra mussels, stingrays

Bites, sharks and other fish, snakes, lobster or crabs.

Electrocution, electric rays, electric eels.

Saturday, April 7, 2007

Swimming Lessons

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, 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 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.