Le Bozec S, Lesne J, Bouisset S
Laboratoire de Physiologie du Mouvement, Université Paris-Sud, 91405 Orsay, France.
Neurosci Lett. 2001 Apr 27;303(1):72-6. doi: 10.1016/s0304-3940(01)01697-4.
The purpose of this study was to explore how the muscles which control postural body segments are activated during bilateral isometric ramp pushes exerted with the upper limbs by seated subjects. The paradigm under study presents the advantage that the subject is in a quasi-static posture, and since upper limbs are stretched out, the dynamic phenomena, which might occur, can only originate from the rest of the body, which means from the postural chain. A dynamometer was used to measure the horizontal force, Fx, exerted on the bar, and a custom-designed force-plate was used to measure global reaction forces (Rx) and displacement of the centre of pressure (Xp) along the antero-posterior axis. Electromyograms (EMGs) were picked up by bipolar surface electrodes from 14 muscles crossing the lower limb, pelvis, trunk and upper limb joints. It was shown that transient push efforts require monotonous EMG increase in postural as well as in focal muscles. The EMG sequence starts with the postural muscles and ends with the focal ones. The postural EMG sequence is anticipatory. It is concluded that the EMG sequence is programmed according to the task parameters, and that its role is to counteract in advance the perturbing effect of the effort, in order to allow the effort to be performed efficiently. It is suggested that excitation between the postural muscles is distributed according to their biomechanical role in relation to the supports.
本研究的目的是探讨在坐位受试者用上肢进行双侧等距斜坡推压时，控制身体姿势节段的肌肉是如何被激活的。所研究的范式具有这样的优势，即受试者处于准静态姿势，并且由于上肢伸展，可能出现的动态现象只能源于身体的其余部分，也就是姿势链。使用测力计测量施加在横杆上的水平力Fx，并使用定制设计的测力板测量全局反作用力（Rx）以及压力中心（Xp）沿前后轴的位移。通过双极表面电极从跨越下肢、骨盆、躯干和上肢关节的14块肌肉采集肌电图（EMG）。结果表明，短暂的推压动作需要姿势肌和局部肌肉的肌电图单调增加。肌电图序列从姿势肌开始，以局部肌肉结束。姿势肌电图序列具有预期性。得出的结论是，肌电图序列是根据任务参数进行编程的，其作用是提前抵消用力的干扰效应，以便有效地进行用力动作。有人提出，姿势肌之间的兴奋根据它们相对于支撑的生物力学作用进行分布。
