Effect of smoothing window length on RMS EMG amplitude estimates

Describes the results of a study on the influence of smoothing window length on the signal-to-noise ratio (SNR) of electromyogram (EMG) amplitude estimates. In a previous experiment, surface EMG waveforms were recorded for non-fatiguing, constant-force, isometric contraction of the biceps and triceps muscles. Based on these data, four different EMG processors were studied using smoothing window length durations spanning 24-500 ms. Results show that the SNR increases in a square root fashion with smoothing window length, as predicted by classical theory. These results are useful in choosing the length of the smoothing window in traditional surface EMG studies, and to adaptively tune the smoothing window length when the EMG amplitude is time-varying.