Functional coupling of motor units is modulated during walking in human subjects
Functional coupling of motor units is modulated during walking in human subjects
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DOI：
10.1152/jn.00844.2002
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发表时间：
2003-02-01
影响因子：
2.5
通讯作者：
Nielsen, JB
中科院分区：
文献类型：
--
作者：
Halliday, DM;Conway, BA;Nielsen, JB
研究了健康人行走过程中腿部肌肉肌电图（EMG）对耦合的时域和频域分析。对于来自胫骨前肌（TA）的两个独立的表面肌电信号，从相干测量中估计的耦合在小于或等于50 Hz的频率下观察到，在大约8至15和15至20 Hz的两个频段内出现可识别的峰值。TA记录之间的一致性在挥杆结束时最大，在挥杆早期减弱，在挥杆中期基本不存在。在由成对的TA肌电图记录构建的时域估计中，观察到一个指示运动单元同步的持续时间较短的中央峰。运动单元耦合的这一特征在摆动中也减少了。在三头肌、股四头肌和腘绳肌的成对记录中，观察到与成对TA记录相似的相关性模式。然而，在由踝关节屈/伸肌和膝关节伸/屈肌分别记录的肌电图记录中，没有观察到明显的耦合。这些结果表明，对于TA，在摆动期间招募的运动单元的功能耦合中存在调制。这些数据还表明，在行走过程中，属于不同肌肉的人类运动神经元只是弱耦合。腿部肌肉活动之间缺乏广泛的短期同步可能为人类步态模式的高度适应性提供了基础。
Time- and frequency-domain analysis of the coupling between pairs of electromyograms (EMG) recorded from leg muscles was investigated during walking in healthy human subjects. For two independent surface EMG signals from the tibialis anterior (TA) muscle, coupling estimated from coherence measurements was observed at frequencies less than or equal to50 Hz, with identifiable peaks occurring in two frequency bands ranging approximately from 8 to 15 and 15 to 20 Hz. The coherence between TA recordings was greatest toward the end of swing, reduced in early swing, and largely absent in midswing. In time-domain estimates constructed from paired TA EMG recordings, a short-lasting central peak indicative of motor-unit synchronization was observed. This feature of motor-unit coupling was also reduced in mid swing. In paired recordings made among triceps surae, quadriceps, and hamstring muscles, a similar pattern of correlation to that for paired TA recordings was observed. However, no significant coupling was observed in recordings for which one EMG recording was made from an ankle flexor/extensor muscle and the other from a knee extensor/flexor muscle. These results demonstrate that for TA a modulation exists in the functional coupling of motor units recruited during swing. The data also indicate that human motoneurons belonging to different muscles are only weakly coupled during walking. This absence of widespread short-term synchronization between the activities of muscles of the leg may provide a basis for the highly adaptive nature of human gait patterns.