Differential regulation of cutaneous and H-reflexes during leg cycling in humans
Differential regulation of cutaneous and H-reflexes during leg cycling in humans
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DOI：
10.1152/jn.2001.85.3.1178
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发表时间：
2001-03-01
影响因子：
2.5
通讯作者：
Chua, R
中科院分区：
文献类型：
--
作者：
Zehr, EP;Hesketh, KL;Chua, R
在人类站立、行走、跑步和腿部骑行期间，反射根据任务和时间进行调节。皮肤反射和霍夫曼（H-）反射都受到运动和任务的调节。然而，最近的证据表明，皮肤和H-反射的调制模式可能是不同的。我们试图通过减少运动阶段的影响和改变静态和动态（腿部循环）条件下的背景肌肉激活水平（低和高）来澄清这个问题。记录踝伸肌比目鱼肌和内侧腓肠肌（MG）和膝伸肌股外侧肌（VL）的肌电图。在静止腿骑自行车的下行过程中诱发反射。皮肤反射与5 × 1.0毫秒脉冲在300赫兹的列车传递到远端胫神经，而H反射引起比目鱼肌刺激与单一的1.0毫秒脉冲。本研究中有两个主要观察结果：1）中潜伏期皮肤反射在静态收缩期间是易化的，但在骑自行车期间显著减弱或逆转为抑制反应（任务依赖性调制）; 2）比目鱼肌H反射在高肌肉激活条件下较大，但不受任务影响（无任务依赖性调制）。因此，在两个反射通路中得到相反的结果。它的结论是，皮肤和H-反射调制不同的机制，在积极的运动样运动。
Reflexes undergo modulation according to task and timing during standing, walking, running, and leg cycling in humans. Both cutaneous and Hoffman (H-) reflexes are modulated by movement and task. However, recent evidence suggests that the modulation pattern for cutaneous and H- reflexes may be different. We sought to clarify this issue by reducing the effect of movement phase and altering the level of background muscle activation (low and high) in static and dynamic (leg cycling) conditions. Electromyography was recorded from the ankle extensors soleus and medial gastrocnemius (MG) and the knee extensor vastus lateralis (VL). Reflexes were evoked during the downstroke of stationary leg cycling. Cutaneous reflexes were evoked with trains of 5 x 1.0 ms pulses at 300 Hz delivered to the distal tibial nerve, whereas H-reflexes were evoked in soleus by stimulation with single 1.0-ms pulses. There were two main observations in this study: 1) middle latency cutaneous reflexes were facilitatory during static contraction but were dramatically attenuated or reversed to suppressive responses during cycling (task-dependent modulation); 2) soleus H- reflexes were larger in the high muscle activation condition but were unaffected by task (no task-dependent modulation). Thus opposite results were obtained in the two reflex pathways. It is concluded that cutaneous and H- reflexes are modulated by different mechanisms during active locomotor-like movements.