初心者における平泳ぎのバイオメカニクス的分析

Six unskilled female college students and one female competitive breaststroker was asked to swim 25m with best efforts in the breaststroke. The movements of the swimmer were filmed through the under-water window with 16mm cine-camera. The filming speed was 50 frames per second. Mean horizontal velocity during a stroke cycle was 0.73 m/sec in the unskilled subjects. This value was corresponded to about 50% of the skilled swimmer. The unskilled subjects swam with a shorter stroke length and a more stroke rate than the competitive breaststroker. The negative correlation was observed between the stroke rate and the stroke length in the unskilled females. The angle between the trunk and the horizontal plane was less in the unskilled than in the skilled. This indicated that the unskilled subjects could not have their bodies as near horizontal as they could during swimming. During the kicking phase, the angle velocity of the knee was greater in the unskilled than in the skilled. However, less horizontal velocity was obtained in the unskilled. From these results, it might be suggested that the unskilled subjects swam at lower velocity during the kicking phase because they could not dorsiflex the ankles during this phase