This study investigated the effect of the time and direction preparation on the electromyographic (EMG) response of the ankle extensor to the backward translation of the support surface in stance. Fifteen healthy adult males aged 35.9 ± 6.2 years participated in this study. In the constant session, the interval between the warning cue and the onset of the backward support surface translation was constant. In the random time session, the interval was randomly assigned in each trial, but the direction was backward across the trials. In the random direction session, the direction was randomly assigned in each trial, but the interval was constant. The EMG amplitude in the time epochs 100-175 ms after translation onset in the random time session was significantly greater than that in the constant session in the soleus, gastrocnemius, and tibialis anterior muscles. The EMG amplitude in the time epochs 120-185 ms after translation onset in the random direction session was significantly greater than that in the constant session in the gastrocnemius and tibialis anterior muscles. This finding indicates that time and direction preparation reduces the late component of the ankle EMG response to backward translation of the support surface. This finding is explained by the supposed process through which uncertainty of the upcoming event causes disinhibition of response or by how time and direction preparation optimizes the magnitude of the long-latency response mediated by the transcortical pathway.

中文翻译：

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时间和方向准备对支撑姿势向后平移时脚踝肌肉反应的影响。

这项研究调查了时间和方向准备对脚踝伸肌对支撑表面向后平移的肌电图（EMG）响应的影响。15名35.9±6.2岁的健康成年男性参加了这项研究。在恒定的过程中，警告提示与后向支撑表面平移开始之间的间隔是恒定的。在随机时间会话中，在每个试验中都随机分配了时间间隔，但是在整个试验中方向是向后的。在随机指导期间，在每个试验中均随机分配了方向，但间隔是恒定的。在随机时间段内翻译开始后100-175 ms的时间段内的EMG幅度明显大于比目鱼腓肠肌恒定段内的EMG幅度，和胫骨前肌。在随机方向上的平移开始后120-185ms的时间段中，EMG振幅明显大于腓肠肌和胫骨前肌中恒定段中的EMG振幅。这一发现表明，时间和方向的准备减少了脚踝肌电图对支撑表面向后平移的反应的后期成分。这一发现是通过假设的过程来解释的，通过该过程，即将发生的事件的不确定性会导致反应抑制，或者通过时间和方向准备如何优化经皮层途径介导的长时延反应的幅度。在随机方向上的平移开始后120-185ms的时间段中，EMG振幅明显大于腓肠肌和胫骨前肌中恒定段中的EMG振幅。这一发现表明，时间和方向的准备减少了脚踝肌电图对支撑表面向后平移的反应的后期成分。这一发现是通过假设的过程来解释的，通过该过程，即将发生的事件的不确定性会导致反应抑制，或者通过时间和方向准备如何优化经皮层途径介导的长时延反应的幅度。在随机方向上的平移开始后120-185ms的时间段中，EMG振幅明显大于腓肠肌和胫骨前肌中恒定段中的EMG振幅。这一发现表明，时间和方向的准备减少了脚踝肌电图对支撑表面向后平移的反应的后期成分。这一发现是通过假设的过程来解释的，通过该过程，即将发生的事件的不确定性会导致反应抑制，或者通过时间和方向准备如何优化经皮层途径介导的长时延反应的幅度。