Power spectrum of the surface EMG in post-polio syndrome.

We evaluated the surface EMG of m. rectus fem., m. tibialis ant. and m. peroneus long. using power density spectral analysis. The frequency distributions were calculated using the fast Fourier transformation for 0-250 Hz. The results of PPS patients were compared to physiological state by ranking in five to 50 Hz subranges. In cases of healthy subjects the maximum signal power falls on 50-100 Hz subrange, the minimum on 200-250 Hz. Depending on the severity of pathological symptoms, the PPS patients showed 2 different types of neuromuscular compensations. More severe pathology caused the spectrum shifts toward the higher frequencies, where the lighter cases manifest the spectrum shifts toward the lower frequencies.