Compensation for interaction torques during single- and multijoint limb movement
Compensation for interaction torques during single- and multijoint limb movement
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DOI：
10.1152/jn.1999.82.5.2310
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发表时间：
1999-11-01
影响因子：
2.5
通讯作者：
Ostry, DJ
中科院分区：
文献类型：
--
作者：
Gribble, PL;Ostry, DJ
在多关节肢体运动（如伸展）期间，由于肢体段围绕其他关节的运动，在一个关节处产生相关力。我们报告了三个实验的结果，在这些实验中，我们评估了肌肉的控制信号被调整以抵消这些“相互作用扭矩”的程度。“人类受试者进行涉及肩部和肘部运动的单关节和多关节指向运动，并且系统地操纵与相互作用扭矩的大小和方向相关的运动参数。我们研究了肩肘肌肉的肌电图（EMG）活动，特别是EMG活动和关节相互作用扭矩之间的关系。第一组实验检查单关节运动。在单关节肘（实验1）和肩（实验2）的运动，阶段性肌电图活动观察到的肌肉跨越固定关节（实验1中的肩部肌肉和实验2中的肘部肌肉）。这种肌肉活动先于运动，并且随着即将到来的相互作用扭矩（由非静止肢体段的运动产生的负载）的大小而在幅度上变化。在第三个实验中，受试者进行多关节运动，包括肩膀和肘部的同时运动。一个关节的运动幅度和速度保持不变，而另一个关节的运动方向是变化的。当肘部运动的方向变化（屈曲与伸展）和肩部运动学保持不变，在肩部肌肉的EMG活动变化取决于肘部运动的方向（因此，在肩部产生的相互作用扭矩的符号）。同样，肘部肌肉的EMG活动变化取决于肩部运动的方向，其中肘部运动学保持不变。从所有三个实验的结果支持的想法，中央控制信号的肌肉进行调整，在一个预测的方式，以补偿相互作用的扭矩-负载在一个关节，取决于其他关节的运动。
During multijoint limb movements such as reaching, relational forces arise at one joint due to the motions of limb segments about other joints. We report the results of three experiments in which we assessed the extent to which control signals to muscles are adjusted to counteract these "interaction torques." Human subjects performed single- and multijoint pointing movements involving shoulder and elbow motion, and movement parameters related to the magnitude and direction of interaction torques were manipulated systematically. We examined electromyographic (EMG) activity of shoulder and elbow muscles and, specifically, the relationship between EMG activity and joint interaction torque. A first set of experiments examined single-joint movements. During both single-joint elbow (experiment 1) and shoulder (experiment 2) movements, phasic EMG activity was observed in muscles spanning the stationary joint (shoulder muscles in experiment 1 and elbow muscles in experiment 2). This muscle activity preceded movement and varied in amplitude with the magnitude of upcoming interaction torque (the load resulting from motion of the nonstationary limb segment). In a third experiment, subjects performed multijoint movements involving simultaneous motion at the shoulder and elbow. Movement amplitude and velocity at one joint were held constant, while the direction of movement about the other joint was varied. When the direction of elbow motion was varied (flexion vs. extension) and shoulder kinematics were held constant, EMG activity in shoulder muscles varied depending on the direction of elbow motion (and hence the sign of the interaction torque arising at the shoulder). Similarly, EMG activity in elbow muscles varied depending on the direction of shoulder motion for movements in which elbow kinematics were held constant. The results from all three experiments support the idea that central control signals to muscles are adjusted, in a predictive manner, to compensate for interaction torques-loads arising at one joint that depend on motion about other joints.