McLean Scott G, Borotikar Bhushan, Lucey Sarah M
School of Kinesiology, The University of Michigan, 401 Washtenaw Avenue, Ann Arbor, MI 48109, USA.
Clin Biomech (Bristol). 2010 Jul;25(6):563-9. doi: 10.1016/j.clinbiomech.2010.02.013. Epub 2010 Mar 31.
Female neuromuscular control during dynamic landings is considered central to their increased ACL injury risk relative to males. There is limited insight, however, into the neuromuscular parameters governing this risk, which may hinder prevention success. This study targeted a new screenable and potentially trainable neuromuscular risk factor. Specifically, we examined whether lower limb muscle pre-motor times, being the time between stimulus presentation and initiation of the muscle EMG burst, elicited during a simple choice reaction task correlated with knee abduction loads during separate single leg landings.
Twenty female NCAA athletes had muscle (n=8) pre-motor time and knee biomechanics data recorded bilaterally during a choice reaction task. Knee biomechanics were also quantified during anticipated and unanticipated single (dominant and non-dominant) leg landings. Mean peak knee abduction loads during landings were submitted to a two-way ANOVA to test for limb and decision effects. Individual regression coefficients were initially computed between-limb-based muscle pre-motor times and peak abduction moments elicited during both the choice reaction and landing tasks. Limb-based linear stepwise regression coefficients were also computed between muscle PMT's demonstrating significant (P<0.05) individual associations and peak knee abduction moments during landings.
Peak knee abduction moments were significantly (P=0.0001) larger during unanticipated (51.25 (7.41) Nm) compared to anticipated (38.93 (9.32) Nm) landings. Peak abduction moments were significantly (P<0.05) correlated with bilateral medial gastrocnemius (r=0.62 dominant; r=0.63 non-dominant) and medial hamstring (r=0.77 dominant; r=0.79 non-dominant) pre-motor times elicited within the choice reaction task. Peak abduction moments during anticipated landings were significantly (P<0.05) correlated with both dominant (r=0.60) and non-dominant (r=0.59) medial hamstring pre-motor times. For unanticipated landings, non-dominant and dominant peak knee abduction moments were significantly correlated with medial hamstring pre-motor time (r=0.78) and combined medial gastroc and medial hamstring pre-motor times (r=0.94) respectively.
Medial muscle pre-motor times during a specific choice reaction task are associated with peak knee abduction loads during separate single leg landings. These muscles appear critical in stabilizing the knee against the extreme dynamic load states associated with such tasks. Targeted screening and training of supraspinal processes governing these muscle pre-motor times may ultimately enable external knee loads associated with landings to be more effectively countered by the overarching neuromuscular strategy.
女性在动态着陆过程中的神经肌肉控制被认为是她们相对于男性而言前交叉韧带（ACL）损伤风险增加的核心因素。然而，对于控制这种风险的神经肌肉参数的了解有限，这可能会阻碍预防措施的成功实施。本研究针对一种新的可筛查且可能可训练的神经肌肉风险因素。具体而言，我们研究了在简单选择反应任务中诱发的下肢肌肉运动前时间（即刺激呈现与肌肉肌电图爆发起始之间的时间）与单独单腿着陆时的膝关节外展负荷是否相关。
20名美国全国大学体育协会（NCAA）的女运动员在选择反应任务期间双侧记录了肌肉（n = 8）运动前时间和膝关节生物力学数据。在预期和非预期的单（优势腿和非优势腿）腿着陆过程中也对膝关节生物力学进行了量化。着陆期间的平均峰值膝关节外展负荷进行双向方差分析以测试肢体和决策效应。最初计算基于肢体的肌肉运动前时间与选择反应和着陆任务期间诱发的峰值外展力矩之间的个体回归系数。还计算了基于肢体的线性逐步回归系数，该系数介于显示出显著（P < 0.05）个体关联的肌肉运动前时间（PMT）与着陆期间的峰值膝关节外展力矩之间。
与预期着陆（38.93（9.32）Nm）相比，非预期着陆（51.25（7.41）Nm）期间的峰值膝关节外展力矩显著更大（P = 0.0001）。峰值外展力矩与选择反应任务中诱发的双侧腓肠肌内侧头（优势侧r = 0.62；非优势侧r = 0.63）和半腱肌内侧头（优势侧r = 0.77；非优势侧r = 0.79）运动前时间显著相关（P < 0.05）。预期着陆期间的峰值外展力矩与优势侧（r = 0.60）和非优势侧（r = 0.59）半腱肌内侧头运动前时间均显著相关（P < 0.05）。对于非预期着陆，非优势侧和优势侧的峰值膝关节外展力矩分别与半腱肌内侧头运动前时间（r = 0.78）和腓肠肌内侧头与半腱肌内侧头联合运动前时间（r = 0.94）显著相关。
特定选择反应任务期间的内侧肌肉运动前时间与单独单腿着陆时的峰值膝关节外展负荷相关。这些肌肉在稳定膝关节以抵抗与此类任务相关的极端动态负荷状态方面似乎至关重要。对控制这些肌肉运动前时间的脊髓上过程进行有针对性的筛查和训练，最终可能使与着陆相关的膝关节外部负荷能够通过整体神经肌肉策略更有效地得到应对。
