De la Barrera E J, Milner T E
Institut de Génie Biomédical, Ecole Polytechnique, Montreal, Que., Canada.
Electroencephalogr Clin Neurophysiol. 1994 Apr;93(2):91-9. doi: 10.1016/0168-5597(94)90071-x.
We investigated the effects of skinfold thickness and electrode orientation on the ability to record selectively from a localized region of a muscle using arrays of surface electrodes. EMG activity elicited by electrical stimulation and by voluntary contraction of the biceps muscle was recorded from subjects with skinfold thicknesses ranging from 2 mm to 21 mm. The selectivity of the surface electrodes increased as the skinfold thickness decreased; action potentials were more rapidly attenuated and underwent less low-pass filtering. As a result, the EMG recorded during a voluntary contraction at one site became less highly correlated with that recorded at neighboring sites as skinfold thickness decreased. We were able to determine the axis of action potential propagation (muscle fiber direction) through comparison of the amplitude and delay of cross-correlation peaks from pairs of colinear electrodes oriented at angles to one another, although the thicker the skinfold the lower the resolution. It was clear that the ability to localize EMG signal sources deteriorated as the amount of subcutaneous fat between the surface recording site and the active muscle fibers increased.
我们研究了皮褶厚度和电极方向对使用表面电极阵列从肌肉局部区域进行选择性记录能力的影响。从皮褶厚度在2毫米至21毫米范围内的受试者记录了由电刺激和肱二头肌自主收缩引发的肌电图活动。随着皮褶厚度减小，表面电极的选择性增加；动作电位衰减更快且经过的低通滤波更少。因此，随着皮褶厚度减小，在一个部位自主收缩期间记录的肌电图与在相邻部位记录的肌电图之间的相关性降低。通过比较相互成一定角度的共线电极对的互相关峰值的幅度和延迟，我们能够确定动作电位传播的轴（肌纤维方向），尽管皮褶越厚分辨率越低。很明显，随着表面记录部位与活跃肌纤维之间皮下脂肪量的增加，肌电图信号源的定位能力会变差。
