Yang J F, Winter D A
Arch Phys Med Rehabil. 1984 Sep;65(9):517-21.
The effect of four amplitude normalization methods on intersubject variability of electromyographic (EMG) profiles in normal gait was examined. Bipolar silver/silver chloride surface electrodes were applied to the rectus femoris, vastus lateralis, biceps femoris, tibialis anterior, and soleus muscles of the right lower extremity, in 11 healthy subjects. The myoelectric signals were telemetered via an FM multichannel biotelemetry system, full-wave rectified and low-pass filtered, then A/D converted together with the footswitch signal. Within-subject ensemble-average patterns were generated from the linear envelope EMG of at least six strides for each subject. Each subject's ensemble average was then normalized to the following: (a) the average EMG over three 50% isometric maximum voluntary contractions (MVC), (b) the EMG per unit isometric moment of force, (c) the peak of the subject ensemble average, (d) the mean of the subject ensemble average. Intersubject variability was quantified for each of the normalization methods by the coefficient of variation (CV). The normalization to either the peak ensemble or the mean ensemble drastically reduced intersubject variability, by 12%-73%. In contrast, normalization to the average EMG during 50% MVC or to the EMG per unit moment increased intersubject variability. It was concluded that the reduction of intersubject variability by appropriate amplitude normalization is possible, thereby increasing the sensitivity of surface EMG as a diagnostic tool in gait analysis.
研究了四种幅度归一化方法对正常步态中肌电图（EMG）轮廓受试者间变异性的影响。在11名健康受试者的右下肢股直肌、股外侧肌、股二头肌、胫骨前肌和比目鱼肌上应用了双极银/氯化银表面电极。肌电信号通过调频多通道生物遥测系统进行遥测，全波整流并低通滤波，然后与脚踏开关信号一起进行A/D转换。从每个受试者至少六步的线性包络肌电图中生成受试者内总体平均模式。然后将每个受试者的总体平均值归一化为以下各项：（a）三次50%等长最大自主收缩（MVC）期间的平均肌电图，（b）每单位等长力矩的肌电图，（c）受试者总体平均值的峰值，（d）受试者总体平均值的均值。通过变异系数（CV）对每种归一化方法的受试者间变异性进行量化。将总体峰值或总体均值归一化可大幅降低受试者间变异性，降低幅度为12% - 73%。相比之下，将50%MVC期间的平均肌电图或每单位力矩的肌电图归一化会增加受试者间变异性。得出的结论是，通过适当的幅度归一化可以降低受试者间变异性，从而提高表面肌电图作为步态分析诊断工具的敏感性。
