Laboratory of Applied Physiology, Graduate School of Human and Environmental Studies, Kyoto University, Kyoto, Japan.
J Electromyogr Kinesiol. 2012 Feb;22(1):74-9. doi: 10.1016/j.jelekin.2011.09.010. Epub 2011 Oct 12.
The aim of the present study was to compare spatial electromyographic (EMG) potential distribution during force production between elderly and young individuals using multi-channel surface EMG (SEMG). Thirteen elderly (72-79years) and 13 young (21-27years) healthy male volunteers performed ramp submaximal contraction during isometric knee extension from 0% to 65% of maximal voluntary contraction. During contraction, multi-channel EMG was recorded from the vastus lateralis muscle. To evaluate alteration in heterogeneity and pattern in spatial EMG potential distribution, coefficient of variation (CoV), modified entropy and correlation coefficients with initial torque level were calculated from multi-channel SEMG at 5% force increment. Increase in CoV and decrease in modified entropy of RMS with increase of exerted torque were significantly smaller in elderly group (p<0.05) and correlation coefficients with initial torque level were significantly higher in elderly group than in young group at moderate torque levels (p<0.05). These data suggest that the increase of heterogeneity and the change in the activation pattern are smaller in elderly individuals than in young individuals. We speculated that multi-channel SEMG pattern in elderly individual reflects neuromuscular activation strategy regulated predominantly by clustering of similar type of muscle fibers in aged muscle.
本研究旨在比较老年和年轻个体在进行等长膝伸肌力量产生时，使用多通道表面肌电图（sEMG）的空间肌电（EMG）电位分布。13 名老年（72-79 岁）和 13 名年轻（21-27 岁）健康男性志愿者进行了从最大自主收缩的 0%到 65%的斜坡亚最大收缩。在收缩过程中，从股外侧肌记录多通道 EMG。为了评估空间 EMG 电位分布的异质性和模式变化，从多通道 sEMG 在 5%的力增量处计算了变异系数（CV）、修正熵和与初始扭矩水平的相关系数。随着施加扭矩的增加，老年组 CV 的增加和 RMS 修正熵的降低显著小于年轻组（p<0.05），并且在中等扭矩水平下，老年组与初始扭矩水平的相关系数显著高于年轻组（p<0.05）。这些数据表明，老年个体的异质性增加和激活模式的变化小于年轻个体。我们推测，老年个体的多通道 sEMG 模式反映了神经肌肉激活策略，主要由老年肌肉中相似类型的肌纤维聚类调节。
