The Effect of Alcohol on the Frequency Components of the Surface Electromyograms

Abstract

This study was designed to investigate the effect of alcohol on the frequency components of the EMGs led from the main limb muscles, with the surface electrodes. Several students of Chiba University served as subjects of experiments. The muscles examined are the main limb muscles, that is, M. flexor digitorum superficialis, M. biceps brachii, M. rectus femoris, M. gastrocnemius and M. tibialis anterior. The muscle activity was amplified by the 13 channel Electroencephalograph during the isometric-isotonic or isometric muscle contraction. The global EMG amplified was led to the automatic frequency analyzer that has five or ten filtering frequency bands (Fig. 1, Fig. 2, Fig. 16). And Fig. 1, Fig. 2 show these frequency characteristics. Here the results analyzed into ten frequency bands do not appear. The global EMGs were analyzed at the time right before drinking and after drinking whisky (39% alcohol) successively.
This study consists of five experiments (Exp. I-Exp. V). In Exp. I, the muscle contractions during 30 min. were sustained under the conditions of controll and drinking alcohol. Now condition of controll means that just before drinking alcohol and the condition of drinking does that during 1-1.5 hours after drinking whisky containing 39% alcohol. The global EMGs were analyzed into five filtering bands at the time of just right before muscle contraction (C curves in Figs. 3, 4, 5, 6) and 10, 20, 30 min. after the beginning of the muscle contraction.
In Exp. II, III, IV and V, the author investigated the effects of alcohol on the frequency spectra of the global EMGs led from M. biceps brachii (Exp. II), M. rectus femoris (Exp. III), M. gastrocnemius (Exp. IV), M. tibialis anterior (Exp. V) with the surface elecrodes.
The conclusion led from experiments are summarized as follows: (1) Each muscle of the limb examined has the nearly constant distribution of frequency spectra under the same conditions of EMG leading. (2) The lowering in the frequency spectra of the global EMG from M. flexor digitorum superficialis during the isometric-isotonic sustained contraction for 30 min. are shown in Fig. 4, and the results are same as other investigaters (Fig. 16). But after drinking alcohol, such a tendency of lowering in frequency spectra was inhibited at the time of 30 min, after the initial contraction (Fig. 4, Fig. 6).
(3) The frequency spectra of the main limb muscles (M. biceps brachii, M. rectus femoris, M. gastrocnemius) were displaced temporary towards higher frequ ency spectra after drinking alcohol (Figs. 7, 8, 9, 10, 12). (4) The tendency of uprearing in frequency specra as those in (3) was almost temporary one and they recovered again before long, but as shown in Fig. 11, sometimes, the tendency of (3) can succeed for a long time comparatively.