Non-stationarity and power spectral shifts in EMG activity reflect motor unit recruitment in rat diaphragm muscle

Yasin B. Seven, Carlos B. Mantilla, Wen Zhi Zhan, Gary C. Sieck

Research output: Contribution to journalArticle

30 Scopus citations

Abstract

We hypothesized that a shift in diaphragm muscle (DIAm) EMG power spectral density (PSD) to higher frequencies reflects recruitment of more fatigable fast-twitch motor units and motor unit recruitment is reflected by EMG non-stationarity. DIAm EMG was recorded in anesthetized rats during eupnea, hypoxia-hypercapnia (10% O2-5% CO2), airway occlusion, and sneezing (maximal DIAm force). Although power in all frequency bands increased progressively across motor behaviors, PSD centroid frequency increased only during sneezing (p<0.05). The non-stationary period at the onset of EMG activity ranged from ~80ms during airway occlusion to ~150ms during eupnea. Within the initial non-stationary period of EMG activity 80-95% of motor units were recruited during different motor behaviors. Motor units augmented their discharge frequencies progressively beyond the non-stationary period; yet, EMG signal became stationary. In conclusion, non-stationarity of DIAm EMG reflects the period of motor unit recruitment, while a shift in the PSD towards higher frequencies reflects recruitment of more fatigable fast-twitch motor units.

Original languageEnglish (US)
Pages (from-to)400-409
Number of pages10
JournalRespiratory Physiology and Neurobiology
Volume185
Issue number2
DOIs
StatePublished - Jan 5 2013

Keywords

  • Diaphragm muscle
  • Electromyography
  • Motor unit recruitment
  • Neuromotor control
  • Power spectrum
  • Stationarity

ASJC Scopus subject areas

  • Neuroscience(all)
  • Physiology
  • Pulmonary and Respiratory Medicine

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