Butterfly stroke

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 center of the body and downward to form the traditionally taught "keyhole".

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 recovery 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.

In the recovery, the arms are swung sideways across the water surface to the front, with the elbows straight. The arms should be swung forward from the end of the underwater movement; the extension of the triceps in combination with the butterfly kick will allow the arm to be brought forwards quickly in a relaxed manner. In contrast to the front crawl recovery, the arm recovery is a ballistic shot, letting gravity and momentum do most of the work. The only other way of lifting the arms and the shoulders out of the water would be by dropping one's hips. Therefore, the recovery, at least the acceleration of the arms, is in no way relaxed . It is important not to enter the water too early, because this would generate extra resistance as the arms move forward in the water against the swimming direction, however, during longer distances, this is difficult to avoid, and it is more important to avoid dropping one's hips. A high elbow recovery, as in front crawl, would be disadvantageous because of the natural undulations that are partially caused by the recovery and the relaxed movement caused by the momentum of a triceps extension. Limitations of the shoulder movement in the human body make such a motion unlikely. The hands should enter into the water with a narrow V shape (at 11 and 1 o'clock, if viewed like a clock) with thumbs entering first and pinkies last.

The arms enter the water with the thumbs first at shoulder width. A wider entry loses movement in the next pull phase, and if the hands touch, it will waste energy. The cycle repeats with the pull phase. However, some swimmers prefer to touch in front, because it helps them catch water – as long as they can do this efficiently, they are not losing anything.

The legs are synchronized with each other which uses a whole different set of muscles. 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 up kick. A smooth undulation fuses 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 they may wish.[8] 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.[9] 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.[10] FINA was then convinced to allow a breaststroke kick in Masters swimming.[11] 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 minimum effort, the swimmer can lift the head to fully break the surface. The swimmer breathes in through the mouth. 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.

Normally, a breath is taken every other stroke. This can be sustained over long distances. Often, breathing every stroke slows the swimmer down. (At a certain level, a breathing stroke becomes just as fast as a nonbreathing stroke; therefore, very experienced competitors, such as Michael Phelps, may breathe every stroke.) Other intervals of breathing practised by elite swimmers include the "two up, one down" approach in which the swimmer breathes for two successive strokes and then keeps their 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 for the finish. Some swimmers can even hold their breaths for an entire race (assuming that it is a short one). To be able to swim with best results it is important to keep one's head down when taking a breath. If the swimmer lifts his or her head too high the swimmer's hips often drop, creating drag, thus slowing the swimmer down. The closer one's head is to the water the better one swims is the general technique used by swimmers.

Swimming butterfly is difficult if the core is not utilized, and correct timing and body movement makes swimming butterfly much easier. The body moves in a wave-like fashion, controlled by the core, and as the chest is pressed down, the hips go up, and the posterior breaks the water surface and transfers into a fluid kick. During the push phase, the chest 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.

Although butterfly is very compatible with diving, the resulting reduction in wave drag does not lead to an overall reduction of drag. In the modern style of the butterfly stroke one does only little vertical movement of the body.

Butterfly uses the regular start for swimming. After the start a gliding phase follows under water, followed by dolphin kicks swim 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.

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 lies 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 15 m 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.

There are four styles of butterfly stroke.

Two main styles of butterfly stroke seen today are: "arm pull up simultaneous with dolphin kick" and "arm pull down simultaneous with dolphin kick".[12]

"Arm pull up simultaneous with dolphin kick": After head goes underwater, both arms go underwater but still higher than head. After first dolphin kick, pull both arms immediately with downward motion. While pulling arms, legs are relaxed, both knees and waist are slightly bent to prepare dolphin kick. After arms push water backward, pull arms up simultaneous with dolphin kick. In this style, turning point from drowning to floating is at the time of downward arm motion.

"Arm pull down simultaneous with dolphin kick": After head goes underwater, both arms go underwater until lower than head. After first dolphin kick, raise both arms with relax. While rising arms, bend both knees and waist to send body back to the surface and prepare dolphin kick. Pull both arms downward while executing dolphin kick. After this sequence, immediately push the water backward. In this style, turning point from drowning to floating is at the time of waist bend.

Two additional styles of butterfly stroke are similar to the two styles above, but without a "second" dolphin kick.[13] This allows the swimmer to conserve energy and be more relaxed.