SEX-DIFFERENCES IN SURFACE EMG INTERFERENCE PATTERN POWER SPECTRUM

Sex differences in the spectral parameters of the surface electromyogr am (EMG) power spectrum were studied during voluntary muscle contracti ons of different strength with rest in between. The influence of two d ifferent types of leads (unipolar and bipolar) on the values of the sp ectral parameters was also investigated under the same experimental co nditions. The subjects were 15 healthy female and 15 healthy male volu nteers. The relationship between the amplitude (root mean square) of t he EMG and the force developed was not linear. The mean values of the median power frequency were lower in women than in men. With both type s of lead, the increase in force was accompanied by a progressive incr ease in median power frequency in male and female subjects. The signif icant differences in spectral parameters observed in the two sexes are probably correlated with anatomic differences.