Fisher Harry, Stephenson Mitchell L, Graves Kyle K, Hinshaw Taylour J, Smith Derek T, Zhu Qin, Wilson Margaret A, Dai Boyi
1Division of Kinesiology and Health, University of Wyoming, Laramie, Wyoming; and 2Department of Theatre and Dance, University of Wyoming, Laramie, Wyoming.
J Strength Cond Res. 2016 Jun;30(6):1670-9. doi: 10.1519/JSC.0000000000001264.
Decreased knee flexion angles during landing are associated with increased anterior cruciate ligament loading. The underlying mechanisms associated with decreased self-selected knee flexion angles during landing are still unclear. The purpose of this study was to establish the relationship between the peak force production at various knee flexion angles (35, 55, 70, and 90°) during isometric squats and the actual knee flexion angles that occur during landing in both men and women. A total of 18 men and 18 women recreational/collegiate athletes performed 4 isometric squats at various knee flexion angles while vertical ground reaction forces were recorded. Participants also performed a jump-landing-jump task while lower extremity kinematics were collected. For women, significant correlations were found between the peak force production at 55 and 70° of knee flexion during isometric squats and the knee flexion angle at initial contact of landing. There were also significant correlations between the peak force production at 55, 70, and 90° of knee flexion during isometric squats and the peak knee flexion angle during landing. These correlations tended to be stronger during isometric squats at greater knee flexion compared with smaller knee flexion. No significant correlations were found for men. Posture-specific strength may play an important role in determining self-selected knee flexion angles during landing for women.
着陆时膝关节屈曲角度减小与前交叉韧带负荷增加有关。着陆时自我选择的膝关节屈曲角度减小的潜在机制仍不清楚。本研究的目的是确定男性和女性在等长深蹲时不同膝关节屈曲角度（35°、55°、70°和90°）下的峰值力量产生与着陆时实际发生的膝关节屈曲角度之间的关系。共有18名男性和18名女性休闲/大学运动员在不同膝关节屈曲角度下进行了4次等长深蹲，同时记录垂直地面反作用力。参与者还进行了跳跃 - 着陆 - 跳跃任务，同时收集下肢运动学数据。对于女性，在等长深蹲时膝关节屈曲55°和70°时的峰值力量产生与着陆初始接触时的膝关节屈曲角度之间存在显著相关性。在等长深蹲时膝关节屈曲55°、70°和90°时的峰值力量产生与着陆时的膝关节最大屈曲角度之间也存在显著相关性。与较小的膝关节屈曲相比，在较大膝关节屈曲的等长深蹲过程中，这些相关性往往更强。男性未发现显著相关性。特定姿势的力量可能在决定女性着陆时自我选择的膝关节屈曲角度方面起重要作用。
