Johnson Kristin A, Nozu Shojiro, Shields Richard K
Department of Physical Therapy and Rehabilitation Science, Roy J. and Lucille A. Carver College of Medicine, The University of Iowa, Iowa City, IA 52242, USA.
Institute of Health and Sports Science & Medicine, Juntendo University, Inzai City 270-1695, Japan.
J Funct Morphol Kinesiol. 2021 Oct 7;6(4):82. doi: 10.3390/jfmk6040082.
Trunk positioning and unexpected perturbations are high-risk conditions at the time of anterior cruciate ligament injury. The influence of trunk positioning on motor control responses to perturbation during dynamic performance is not known. We tested the influence of trunk position on feedforward and feedback control during unexpected perturbations while performing a novel single-limb squatting task. We also assessed the degree that feedforward control was predictive of feedback responses. In the flexed trunk condition, there were increased quadriceps ( < 0.026) and gluteus medius long-latency reflexes ( < 0.001) and greater quadriceps-to-hamstrings co-contraction during feedforward ( = 0.017) and feedback ( = 0.007) time bins. Soleus long-latency reflexes increased more than 100% from feedforward muscle activity regardless of trunk condition. Feedforward muscle activity differentially predicted long-latency reflex responses depending on the muscle (R: 0.47-0.97). These findings support the concept that trunk positioning influences motor control responses to perturbation and that feedback responses may be invariant to the feedforward control strategy.
在交叉韧带前束损伤时，躯干位置和意外扰动是高风险因素。躯干位置对动态运动中扰动的运动控制反应的影响尚不清楚。我们在执行一项新颖的单腿深蹲任务时，测试了躯干位置对意外扰动期间前馈和反馈控制的影响。我们还评估了前馈控制对反馈反应的预测程度。在躯干屈曲状态下，股四头肌（<0.026）和臀中肌长潜伏期反射（<0.001）增加，并且在前馈（=0.017）和反馈（=0.007）时间段内股四头肌与腘绳肌的共同收缩更大。无论躯干状态如何，比目鱼肌长潜伏期反射从前馈肌肉活动增加超过100%。前馈肌肉活动根据肌肉不同地预测长潜伏期反射反应（R：0.47 - 0.97）。这些发现支持了躯干位置影响对扰动的运动控制反应且反馈反应可能与前馈控制策略无关的概念。
