抄録
The purpose of this study was to examine the influences of back plate width on the starting operation in competitive swimming, by using three-dimensional (3D) analysis. This study included 12 male university student swimmers, who usually use the kick-start technique. We filmed the kick-start operation by using three high-speed cameras (300 scenes; shutter speed: 1/500 s). The 3D coordinates of 21 points on each subject’s body were examined by using direct linear transformation. The subjects were instructed to perform the kick start on back plates of different widths: typical width (Normal), narrower than Normal (Narrow), and wider than Normal (Wide).
During the preparation phase, there were significant differences between both Narrow and Normal and Narrow and Wide in the horizontal distance of the center of gravity. During the horizontal acceleration phase, there were significant differences between Normal and Wide. There were significant differences between Narrow and Normal in the horizontal velocity of flight. In addition, take-off at Normal tended to be faster than Narrow and Wide in the horizontal velocity of center of gravity.
During the preparation phase, it was thought that the horizontal distance of the center of gravity reduces as the width of the back plate increases. Additionally, it was suggested that acceleration and velocity in the horizontal direction decrease when the width of the back plate is set different of Normal.
