Some people prefer to float around a pool on their inner tube; while others love the complex movements associated with some swim strokes. The butterfly stroke, for example, requires strength and refined technique to be executed successfully. The stroke is characterized by the undulating motion of the body through the water and the use of both arms simultaneously, combined with a leg kick known as a dolphin kick.
The butterfly stroke is the newest of the four recognized competitive strokes. David Armbruster of the University of Iowa is the coach who is widely acknowledged with inventing the stroke in 1934. It evolved from traditional breaststroke and was originally performed with the breaststroke kick, but in 1935, a swimmer named Jack Seig developed a dolphin kick style, with both legs kicking together. This style is still used today.
Both your arms work simultaneously. A complete arm movement starts with your hands in the water, elbows slightly bent, just in front of your head. Your hands are then pulled downward toward your feet, moving in a keyhole motion. When your hands reach your thighs, they are pulled out of the water and thrown over the water, back to the starting position. Your hands should enter the water at an angle, thumbs first. The entry point for your hands is in front of your head, between the shoulder and nose, with your arms extended. The arm movement is constant throughout the stroke and should continue without pause.
In butterfly, your legs also work simultaneously in an up-and-down motion. Your feet should be pushed together. A two-beat dolphin kick uses two strong kicks: The first kick helps propel your arms over the water in the recovery phase, and the second kick is performed as your arms are moving through the water. Your arm movement and leg kick together result in an undulating motion through the water.
Breathing takes place as your arms are thrown over the water. Your face comes out of the water, with the natural momentum of the stroke helping lift your head. Breaths must be taken quickly because of the continuous nature of the stroke. Swimmers typically breathe on every second stroke but can breathe more or less often.
The rules for swimming butterfly are set by FINA, the Federation International de Natation. For swimming butterfly legally in competition, the arms must be brought forward together over the water and work simultaneously. For turns, the swimmer should touch the wall with both hands together. The legs must also work together, which means they should not alternate during kicks. Swimmers may stay underwater for a maximum of 15 meters at the start of the race and after turns.