Effect of sampling frequency on EMG power spectral characteristics.

During digitization of surface EMG, the signal is converted by an Analog-to-Digital (A/D) convertor at a specific sampling rate. This sampling rate should be selected cautiously because a high rate may include noise signals and a low rate may lead to errors. The present study was undertaken to show the effect of sampling rate on EMG power spectrum. The study was carried out on nine subjects and EMG record was done from deltoid muscle at sampling rates of 4, 6, 8 and 10 KHz during maximal voluntary contraction. Biopotential coupler with a response range of 5 Hz to 2 KHz was used during recording of the EMG signal which was processed later by Fast Fourier Transform software. The study showed a linear relationship between the sampling rate and the mean power frequency (MPF). But there was no distinct effect of sampling rate on mean and root mean square (RMS) of the digitized signal.