Responses in human motor unit activities during movement.

在单个人体拇外展肌（ADM）运动单元中，存在最大发射频率为80Hz的运动单元，力阈值为63% MVC。在ADM、指伸肌（ED）、三角肌(D)和股外侧肌（LV）的运动单元中，检测抽动收缩时间、抽动峰值张力和力阈值的关系。除D肌外，力阈值与收缩时间成反比。除ED肌外，峰值张力与力阈值成正比。每块肌肉的张力峰值与收缩时间的关系不同。在左室肌运动单元中，静力作用后力阈值及其标准差趋于降低。在不同负荷和角速度下的膝关节和踝关节等速运动中，由于负荷和缩短速度的增加，缩短收缩时运动单元的招募顺序与等速收缩时的招募顺序发生了很大的变化。结果表明，运动单元的选择性招募取决于角速度。此外，结果表明，有两种类型的运动单位招募。一只手取决于角速度，另一只手取决于关节角。在等长收缩和等张收缩后的运动单元特征中，快型运动单元抽动收缩时间有增加的趋势，慢型运动单元抽动收缩时间有减少的趋势。在收缩条件下，运动单位的招退顺序不同。通过测量ADM和第一背骨间肌（FDI）运动单元在随意收缩时的放电模式，可以通过神经电刺激人工解决力控制机制。

In single human motor units of abductor digiti minimi(ADM) muscle, there were motor units with maximal firing frequency at 80Hz, and with force threshold at 63% MVC.In motor units of ADM, extensor digitorum(ED), deltoid(D) and lateral vastus(LV) muscles, relationship between twitch contraction time, twitch peak tension and force threshold were examined. Force threshold was inversely proportional to contraction time except D muscle. Peak tension was proportional to force threshold except ED muscle. Relation between peak tension and contraction time was different in each muscle. In motor units of LV muscle, force threshold and its standard deviation tended to decrease following static force exersions. During isokinetic movement of knee and ankle joint at various load and angular velocities, recruitment order of motor units at shortening contractions widely changed from that at isometric contractions due to increase in load and shortening velocities. The results imply the selective recruitment of motor units depending on angular velocities. Also, the results suggest that there are two kinds of motor units recruited. One hand depends on the angular velocities, and the other hand depends on the joint angles. In characteristics of motor unis in ADM muscle following isometric and isotonic contractions, twitch contraction time tended to increase in fast type motor units, and it tended to decrease in slow type motor units. Recruitment and derecruitment order of motor units were different in the conditions of contractions. Due to the measurement of firing patterns of motor units in ADM and first dorsal interosseus(FDI) muscles during voluntary contractions, force control mechanisms were able to solve artificially by electrical nerve stimulations.