The effect of epoch length on time and frequency domain parameters of electromyographic and mechanomyographic signals

Joshua L. Keller, Terry J. Housh, Clayton L. Camic, Haley C. Bergstrom, Doug B. Smith, Cory M. Smith, Ethan C. Hill, Richard J. Schmidt, Glen O. Johnson, Jorge M. Zuniga

Research output: Contribution to journalArticle

1 Scopus citations

Abstract

The selection of epoch lengths affects the time and frequency resolution of electromyographic (EMG) and mechanomyographic (MMG) signals, as well as decisions regarding the signal processing techniques to use for determining the power density spectrum. No previous studies, however, have examined the effects of epoch length on parameters of the MMG signal. The purpose of this study was to examine the differences between epoch lengths for EMG amplitude, EMG mean power frequency (MPF), MMG amplitude, and MMG MPF from the VL and VM muscles during MVIC muscle actions as well as at each 10% of the time to exhaustion (TTE) during a continuous isometric muscle action of the leg extensors at 50% of MVIC. During the MVIC trial, there were no significant (p > 0.05) differences between epoch lengths (0.25, 0.50, 1.00, and 2.00-s) for mean absolute values for any of the EMG or MMG parameters. During the submaximal, sustained muscle action, however, absolute MMG amplitude and MMG MPF were affected by the length of epoch. All epoch related differences were eliminated by normalizing the absolute values to MVIC. These findings supported normalizing EMG and MMG parameter values to MVIC and utilizing epoch lengths that ranged from 0.25 to 2.00-s.

Original languageEnglish (US)
Pages (from-to)88-94
Number of pages7
JournalJournal of Electromyography and Kinesiology
Volume40
DOIs
StatePublished - Jun 2018

Keywords

  • EMG
  • Epoch length
  • MMG

ASJC Scopus subject areas

  • Neuroscience (miscellaneous)
  • Biophysics
  • Clinical Neurology

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    Keller, J. L., Housh, T. J., Camic, C. L., Bergstrom, H. C., Smith, D. B., Smith, C. M., Hill, E. C., Schmidt, R. J., Johnson, G. O., & Zuniga, J. M. (2018). The effect of epoch length on time and frequency domain parameters of electromyographic and mechanomyographic signals. Journal of Electromyography and Kinesiology, 40, 88-94. https://doi.org/10.1016/j.jelekin.2018.04.003