Brown T N, McLean S G, Palmieri-Smith R M
School of Kinesiology, The University of Michigan, Ann Arbor, MI, USA.
School of Kinesiology, The University of Michigan, Ann Arbor, MI, USA.
J Sci Med Sport. 2014 Jul;17(4):408-13. doi: 10.1016/j.jsams.2013.05.010. Epub 2013 Jul 10.
Anterior cruciate ligament injury prevention programs purportedly improve knee joint loading through beneficial modification of lower limb neuromuscular control strategies and joint biomechanics, but little is known about how these factors relate during single-legged landings. Thus, we examined the relationship between explicit lower limb muscular pre-activity patterns and knee joint biomechanics elicited during such landings.
Randomized controlled trial.
Thirty-five female athletes had 3D knee joint biomechanics and lower limb EMG data recorded during a series of single-leg landings. Regression analysis assessed the relationship between pre-activity of vastus lateralis, lateral hamstring and rectus femoris with peak knee flexion angle and moment, and external anterior tibial shear force. Vastus lateralis, lateral hamstring and vastus lateralis:lateral hasmtring co-contraction assessed the relationship with knee abduction angle and moment.
Greater pre-activity of rectus femoris predicted increased peak anterior tibial shear force (R(2)=0.235, b=2.41 and P=0.003) and reduced knee flexion moment (R(2)=0.131, b=-0.591, and P=0.032), while greater lateral hamstring predicted decreased peak knee flexion angle (R(2)=0.113, b=8.96 and P=0.048). No EMG pre-activity parameters were predictors (P>0.05) for knee abduction angle and moment.
Current outcomes suggest reducing reliance on quadriceps activation may be beneficial during single-legged landings. It also, however, may be required for adequate joint stability during such maneuvers. Further research is needed to determine if inadequate hamstring activation, rather than elevated quadriceps activation, leads to hazardous loading during single-legged landings.
前交叉韧带损伤预防方案据称可通过有益地改变下肢神经肌肉控制策略和关节生物力学来改善膝关节负荷，但对于单腿落地时这些因素之间的关系知之甚少。因此，我们研究了明确的下肢肌肉预激活模式与单腿落地时引发的膝关节生物力学之间的关系。
随机对照试验。
35名女性运动员在一系列单腿落地过程中记录了三维膝关节生物力学和下肢肌电图数据。回归分析评估了股外侧肌、股二头肌外侧头和股直肌的预激活与膝关节最大屈曲角度和力矩以及胫骨前外侧剪切力之间的关系。股外侧肌、股二头肌外侧头以及股外侧肌与股二头肌外侧头的共同收缩评估了与膝关节外展角度和力矩的关系。
股直肌更大的预激活预示着胫骨前外侧剪切力峰值增加（R² = 0.235，b = 2.41，P = 0.003）以及膝关节屈曲力矩减小（R² = 0.131，b = -0.591，P = 0.032），而股二头肌外侧头更大的预激活预示着膝关节最大屈曲角度减小（R² = 0.113，b = 8.96，P = 0.048）。没有肌电图预激活参数是膝关节外展角度和力矩的预测指标（P>0.05）。
目前的结果表明，在单腿落地时减少对股四头肌激活的依赖可能是有益的。然而，在这种动作中，为了获得足够的关节稳定性，这可能也是必要的。需要进一步研究以确定在单腿落地时，是腘绳肌激活不足而非股四头肌激活增加导致了危险的负荷。
