On the reflex coactivation of ankle flexor and extensor muscles induced by a sudden drop of support surface during walking in humans
On the reflex coactivation of ankle flexor and extensor muscles induced by a sudden drop of support surface during walking in humans
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DOI：
10.1152/japplphysiol.00670.2003
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发表时间：
2004-02-01
影响因子：
3.3
通讯作者：
Yano, H
中科院分区：
文献类型：
--
作者：
Nakazawa, K;Kawashima, N;Yano, H
最近的研究表明，在人类行走的早期站立阶段，踝关节屈肌和伸肌的拉伸反射反应是共同增强的，这表明这些共同增强的反射反应有助于脚跟撞击周围的足部稳定。为了验证当支撑面突然不稳定时，是否真的会在踝关节屈肌和伸肌中诱发拉伸反射通路介导的反射反应，我们研究了人类站立行走早期支撑面突然下降后引起的肌电反应。当受试者在走道上行走时，特别设计的可移动支撑面在站立初期意外下降10毫米。结果显示，在跌落冲击（< 50 ms）后，在受干扰的腿的踝关节屈肌和伸肌中均观察到一致的短潜伏期反射肌电图反应。特别有趣的是，胫骨前肌出现了明显的反应，尽管该肌肉在站立阶段几乎没有显示背景肌电活动。这些结果表明，当步行过程中脚跟撞击后支撑面意外不稳定时，脚踝肌肉的反射活动肯定会起作用。这些反射反应很可能是由早期站立阶段踝关节肌肉的伸展反射通路介导的，并被认为与人类行走时踝关节周围的稳定有关。
Recent studies have revealed that the stretch reflex responses of both ankle flexor and extensor muscles are coaugmented in the early stance phase of human walking, suggesting that these coaugmented reflex responses contribute to secure foot stabilization around the heel strike. To test whether the reflex responses mediated by the stretch reflex pathway are actually induced in both the ankle flexor and extensor muscles when the supportive surface is suddenly destabilized, we investigated the electromyographic (EMG) responses induced after a sudden drop of the supportive surface at the early stance phase of human walking. While subjects walked on a walkway, the specially designed movable supportive surface was unexpectedly dropped 10 mm during the early stance phase. The results showed that short-latency reflex EMG responses after the impact of the drop ( < 50 ms) were consistently observed in both the ankle flexor and extensor muscles in the perturbed leg. Of particular interest was that a distinct response appeared in the tibialis anterior muscle, although this muscle showed little background EMG activity during the stance phase. These results indicated that the reflex activities in the ankle muscles certainly acted when the supportive surface was unexpectedly destabilized just after the heel strike during walking. These reflex responses were most probably mediated by the facilitated stretch reflex pathways of the ankle muscles at the early stance phase and were suggested to be relevant to secure stabilization around the ankle joint during human walking.