Suppression of stimulus artifact contaminating electrically evoked electromyography

Jie Liu, Sheng Li, Xiaoyan Li, Cliff Klein, William Z. Rymer, Ping Zhou*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

18 Scopus citations


BACKGROUND: Electrical stimulation of muscle or nerve is a very useful technique for understanding of muscle activity and its pathological changes for both diagnostic and therapeutic purposes. During electrical stimulation of a muscle, the recorded M wave is often contaminated by a stimulus artifact. The stimulus artifact must be removed for appropriate analysis and interpretation of M waves. OBJECTIVES: The objective of this study was to develop a novel software based method to remove stimulus artifacts contaminating or superimposing with electrically evoked surface electromyography (EMG) or M wave signals. METHODS: The multiple stage method uses a series of signal processing techniques, including highlighting and detection of stimulus artifacts using Savitzky-Golay filtering, estimation of the artifact contaminated region with Otsu thresholding, and reconstruction of such region using signal interpolation and smoothing. The developed method was tested using M wave signals recorded from biceps brachii muscles by a linear surface electrode array. To evaluate the performance, a series of semi-synthetic signals were constructed from clean M wave and stimulus artifact recordings with different degrees of overlap between them. RESULTS: The effectiveness of the developed method was quantified by a significant increase in correlation coefficient and a significant decrease in root mean square error between the clean M wave and the reconstructed M wave, compared with those between the clean M wave and the originally contaminated signal. The validity of the developed method was also demonstrated when tested on each channel's M wave recording using a linear electrode array. CONCLUSIONS: The developed method can suppress stimulus artifacts contaminating M wave recordings.

Original languageEnglish (US)
Pages (from-to)381-389
Number of pages9
Issue number2
StatePublished - 2014


  • M wave
  • electromyography (EMG)
  • stimulus artifact suppression

ASJC Scopus subject areas

  • Clinical Neurology
  • Rehabilitation
  • Physical Therapy, Sports Therapy and Rehabilitation


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