Changes in muscle activity with increase in leg stiffness during hopping
Changes in muscle activity with increase in leg stiffness during hopping
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DOI：
10.1016/j.neulet.2007.02.064
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发表时间：
2007-05-11
影响因子：
2.5
通讯作者：
Suzuki, Shuji
中科院分区：
文献类型：
--
作者：
Hobara, Hiroaki;Kanosue, Kazuyuki;Suzuki, Shuji
虽然哺乳动物运动中腿的弹簧状腿行为已经有了很好的记录，但其神经基础仍然不明确。本研究的目的是检查腿刚度控制在跳跃。七名男性受试者在原地进行两条腿跳跃，在他们的首选频率与两个不同的接触时间的立场相，首选和短的（PCT和SCT，分别）。基于弹簧模型，腿部刚度是根据受试者的身体质量、地面接触和飞行时间计算的。记录腓肠肌内侧肌（MG）、比目鱼肌（SOL）和胫骨前肌（TA）的表面肌电（EMG）活动。SCT条件下的腿部刚度高于PCT条件。SCT条件的特点是高EMG活动的MG和SOL在前和后着陆阶段，达到峰值约50毫秒。另一方面，TA的活动是低的，在整个接触阶段相比，MG和SOL，其峰值约50毫秒后着陆显着低于SCT条件比PCT条件。我们的结论是：（1）腿部僵硬是由中枢程序性肌肉预激活的变化调节的，也可能是由小腿三头肌短潜伏期牵张反射反应的伴随变化调节的;（2）拮抗性TA的共同收缩在腿部僵硬控制中不起主要作用。(c)2007爱思唯尔爱尔兰有限公司保留所有权利。
While the spring-like leg behavior of legs in mammalian locomotion has been well documented, its neural basis remains ambiguous. The purpose of the present study was to examine leg stiffness control during hopping. Seven male subjects performed in place two-legged hopping at their preferred frequency with two different contact times of the stance phase, preferred and short ones (PCT and SCT, respectively). Based on a springmass model, leg stiffness was calculated from the subjects' body mass, ground contact and flight times. Surface electromyographic (EMG) activities of the medial gastrocnemius (MG), soleus (SOL) and tibialis anterior (TA) muscles were recorded. Leg stiffness was higher in the SCT condition than in the PCT condition. The SCT condition was characterized by high EMG activity of MG and SOL at both pre- and post-landing phases, which peaked at about 50 ms. On the other hand, the activity of TA was low throughout the contact phase as compared with those of MG and SOL, and its peak value around 50 ms after landing was significantly lower for the SCT condition than for the PCT condition. We conclude that (1) the leg stiffness is regulated by a change in centrally programmed muscle preactivation and probably also by a concomitant change in the short-latency stretch reflex response of the triceps surae muscles, and (2) the co-contraction of antagonistic TA does not play a major role in leg stiffness control. (c) 2007 Elsevier Ireland Ltd. All rights reserved.