記録水準の異なるハンマー投競技者のターン動作におけるハンマーヘッド加速動作のキネマティクス分析

抄録

　The purpose of this study was to investigate the acceleration motion of the hammer head during the turn phase in hammer throwers with record levels covering a wide range from the world’s best to Japanese student level. The characteristics of the acceleration motion of high-record throwers were also analyzed. Forty-four male throwers (throwing record, 80.50-44.17 m) participated in the study as subjects. Their throwing motions were videotaped on high-speed VTR cameras (250-300 fps), and three-dimensional coordinates were calculated using a DLT method. The kinematic parameters of the hammer, upper limbs and trunk were calculated, and the correlations between them and throwing record were examined. The fundamental factors clarified were as follows: (1) The higher the throwing record became, it was more evident that the hammer, the shoulder and the hip were pointed in the throwing direction at the moment of right foot contact (Ron), i.e. the starting point of hammer head acceleration. The more the hammer turned in the throwing direction at Ron, the greater the angular displacement of the hammer, shoulder and hip rotation became during the double support phase (DSP). (2) The higher the throwing record became, the angular displacement of shoulder rotation and the average angular velocity of shoulder rotation became greater at the Ron-lowest position of the hammer head (LP). (3) The higher the throwing record became, the maximum velocity of the left and right shoulder joint center on the horizontal plane and the angular velocity of the trunk back lean became higher at Ron-LP. (4) The higher the throwing record became, the angular displacement of the trunk right lean and the average angular velocity of the trunk right lean became higher at DSP. Therefore, it is considered that the hammer head acceleration motion of high-record hammer throwers is characterized by the body rotation and trunk lean at DSP.