[An optimized filter band analyzer for quantification of localized muscle fatigue]

A filter bank analyzer is described which determines the central frequency of the electromyographic signal as a characteristic value and exhibits it continuously. In contrast with previous methods, this analyzer needs only a narrow frequency band and few filters to obtain exact quantitative results. The filter bank parameters are determined by adapting them to the amplitude spectra of electromyograms during fatiguing dynamic muscle work. Six parallel band-pass filters transmit the expected average spectral function, with minimized differences in the frequency range from 18 Hz to 140 Hz. The systematic error of the center frequency amounts to less than 0.5%, when using precision filters with high roll-off. An example compares the shift of center frequency method with the fatigue index of myoelectrical activity.