Laboratory of Neurophysiology, Graduate School of Human and Environmental Studies, Kyoto University, Kyoto, Japan.
Neurosci Lett. 2012 Apr 4;513(2):146-50. doi: 10.1016/j.neulet.2012.02.020. Epub 2012 Feb 16.
The purpose of this study was to examine the influence of subthreshold electrical stimulation on the force fluctuations and motor-unit discharge variability during low-level, steady contraction of the plantar flexor muscles. Seven subjects performed a force-matching task of isometric plantar flexion at 5% of maximal voluntary contraction with and without random electrical stimulation applied to the tibial nerve. During the task, the motor unit action potential was continuously recorded with fine-wire electrodes, and the inter-spike intervals of a single motor unit were calculated. The coefficient of variation (CV) of the force fluctuations and the inter-spike intervals of the motor unit discharge were significantly decreased by the intervention of subthreshold electrical stimulation, although there were no changes in the mean values. These results suggest that subthreshold stimulation reduced the motor-unit discharge variability, which in turn, increased the steadiness of the force.
本研究旨在探讨阈下电刺激对足底屈肌低水平、稳定收缩时力波动和运动单位放电变异性的影响。7 名受试者在施加和不施加随机电刺激的情况下，以最大自主收缩的 5%进行等长足底屈曲的力量匹配任务。在任务过程中，使用细电线电极连续记录运动单位动作电位，并计算单个运动单位的尖峰间隔。尽管平均值没有变化，但阈下电刺激显著降低了力波动和运动单位放电尖峰间隔的变异系数 (CV)。这些结果表明，阈下刺激降低了运动单位放电的可变性，从而提高了力的稳定性。
