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Breaststroke is a swimming style in which the swimmer is on his or her chest and the torso does not rotate. It is the most popular recreational style due to the swimmer's head being out of the water a large portion of the time, and that it can be swum comfortably at slow speeds. In most swimming classes, beginners learn either the breaststroke or the front crawl first. However, at competition level, swimming breaststroke at speed requires comparable endurance and strength to other strokes. Some people refer to breaststroke as the "frog" stroke, as the arms and legs move somewhat like a frog swimming in the water. The stroke itself is the slowest of any competitive strokes and thought to be the oldest of all swimming strokes.〔(Maglischo, Ernest W. ''Swimming fastest'' p. 219 )〕〔(Gifford, Clive ''Swimming'' p. 18 )〕 ==Speed and ergonomics== Breaststroke is the slowest of the four official styles in competitive swimming. The fastest breaststrokers can swim about 1.57 metres per second. Although it is the slowest of the four competitive strokes, it is commonly agreed that it is by far the most difficult to do correctly. It is also often the hardest to teach to rising swimmers after butterfly due to the importance of timing and the coordination required to move the legs properly. In the breaststroke, the swimmer leans on the chest, arms breaking the surface of the water slightly, legs always underwater and the head underwater for the second half of the stroke. The kick is sometimes referred to as a "frog kick" because of the resemblance to the movement of a frog's hind legs; however, when done correctly it is more of a "whip kick" due to the whip-like motion that moves starting at the core down through the legs. The body is often at a steep angle to the forward movement, which slows down the swimmer more than any other style. Professional breaststrokers use abdominal muscles and hips to add extra power to the kick, although most do not perfect this technique until the collegiate level. This much faster form of breaststroke is referred to as "wave-action" breaststroke and fully incorporates the whip-kick. A special feature of competitive breaststroke is the underwater pullout. From the streamline position, one uses the arms to pull all the way down past the hips. As the arms are pulling down, one downward dolphin kick is allowed (as of the 2005 season), though still optional; more than one dolphin kick will result in disqualification. This is followed by the recovery of the arms to the streamline position once more with a breaststroke kick. The pullout is also called the "pull down." The pullout at the start and after the turns contributes significantly to the swimming times. Open turns can be easily performed at the walls, but both hands must make contact with the wall. Therefore, one way to improve swimming times is to focus on the start and the turns. File:Breaststroke.gif File:Breaststroke2.gif File:Breaststroke3.gif 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Breaststroke」の詳細全文を読む スポンサード リンク
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