原著論文
世界一流女子テニスプレーヤーのフォアハンド・ストロークのキネマティクス的分析
―クローズドスタンスとオープンスタンスの比較―
1998 年 2 巻 4 号 p. 242-251
詳細
1998 年 2 巻 4 号 p. 242-251
The purpose of this study was to investigate characteristics of forehand ground strokes with closed- and open-stance for world-top female tennis players in official games. Forehand strokes of female players at Japan Open '96 and Fed Cup (Japan vs Germany) in Tokyo were videotaped with two high-speed VTR cameras. World-top female players studied were S. Graf, A. Huber, K. Date, A. Frazier, N. Sawamatsu, A. Sugiyama, N. Kijimuta. They all were right-handed. Three-dimensional coordinates of body landmarks of the players and points on the rackets and ball were obtained with a DLT method. Kinematic variables calculated were stroking time, stance parameters, shoulder, hip and foot rotation angles and twist angles of the trunk and shoulders.
The results were summarized as follows:
1) In open-stance forehand stroke, time elapsed in take back phase was shorter (p < 0.05), and feet contact were faster than those of closed-stance forehand stroke.
2) Changes in shoulder and hip rotation angles showed no significant difference between closed- and open-stance forehand strokes. Feet in closed-stance forehand stroke were placed perpendicular to the baseline (−108 ± 26.1°) at feet contact, while they were placed parallel to the baseline (−21 ± 29.3°) in open-stance forehand stroke (p < 0.05).
3) Displacement of the center of gravity in hitting direction and stance length were larger in closed-stance forehand stroke than in open-stance forehand stroke (p < 0.001, p < 0.05).
4) Shoulder motion in closed-stance forehand stroke was characterized by forward twisting, while shoulders in open-stance forehand stroke were twist backward during take back phase, followed by forward motion during forward swing phase (p < 0.05). Twisting range of shoulders in open-stance forehand stroke was larger than those of closed-stance forehand stroke (p < 0.05).
From these results, it was suggested that the difference in the twisting motion is caused by the stance, and that open-stance forehand stroke with shorter stroking time and faster preparation of the feet may be more appropriate to recent tennis games.
