Comparisons of ground reaction force between successful and unsuccessful lifts in snatch and clean-and-jerk in weightlifting

Abstract

<p>目的：利用符合舉重運動特性的單軸測力平台，探討菁英選手在抓舉與挺舉時，成功與失敗地面反作用力參數之差異。方法：11名大專舉重選手為本研究參與者。參與者進行符合正式比賽規定的抓舉與挺舉動作時，雙腳需分別站立於長2公尺寬1公尺的舉重專用測力平台。每位參與者先完成抓舉再進行挺舉，每次試舉過程利用測力平台收集地面反作用力，並計算各階段力量峰值、發力率、壓力中心前後位移、雙腳寬度距離、右腳力量比例，再進行差異比較。結果：成功抓舉在第一拉期力量峰值、接槓時間顯著大於失敗；高比例的參與者，在接槓期力量峰值亦小於失敗。成功挺舉在上搏接槓期力量峰值顯著小於失敗。結論：失敗最高的階段發生在接槓期。抓舉應提高第一拉期的力量，以爭取更多接槓時間。接槓期應減少負荷力量；在上挺接槓分腿支撐時，可將槓鈴與壓力中心向後移動，並維持壓力中心接近於雙腳跨距中間偏前的位置。舉重專用測力平台能全程給予選手發力方式的回饋，有利於修正技術。</p> <p> </p><p>Purpose: To explore the differences in ground reaction force parameters between successful and unsuccessful lifts during the snatch and clean-and-jerk using an internally developed uniaxial force platform. Methods: Eleven elite college-level weightlifters were recruited in this study. They were asked to stand on a 2m1m force platform to perform the snatch and clean-and-jerk with self-selected weights by following the official competition rules. The maximal total ground reaction force (vGRF), rate of force development, the center of pressure, feet distance, and force distribution of the right foot were calculated and compared across different phases. Results: In the snatch, the peak vGRF of the first pull and the catching time in successful lifts were significantly higher than in unsuccessful ones. Moreover, the peak vGRF of catching in successful lifts was lower than in unsuccessful lifts. In successful clean-and-jerk, the peak vGRF of catching during clean in successful attempts was lower than in unsuccessful lifts. Conclusion: The phase with the highest failure rate occurred during the catch phase. In the snatch, increasing the force during the first pull may allow for more time in the catching phase. It is also recommended that the loading force should be reduced during the catching phase. In the split jerk, results showed moving the barbell and the center of pressure backward while maintaining the center of pressure slightly forward of the midpoint between the feet can improve stability. It is recommended that during weightlifting training, the internally developed force platform serves as a valuable tool to provide feedback on biomechanical indicators such as force development and help coaches and athletes refine weightlifting techniques in real-time.</p> <p> </p>