Muscle fatigue increases beta-band coherence between the firing times of simultaneously active motor units in the first dorsal interosseous muscle

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Title: Muscle fatigue increases beta-band coherence between the firing times of simultaneously active motor units in the first dorsal interosseous muscle
Authors: McManus, Lara M.
Hu, Xiaogang
Rymer, William
Suresh, Nina
Lowery, Madeleine M.
Permanent link: http://hdl.handle.net/10197/8212
Date: 1-Jun-2016
Abstract: Synchronization between the firing times of simultaneously active motor units (MUs) is generally assumed to increase during fatiguing contractions. To date, however, estimates of MU synchronization have relied on indirect measures, derived from surface electromyographic (EMG) interference signals. This study used intramuscular coherence to investigate the correlation between MU discharges in the first dorsal interosseous muscle during and immediately following a submaximal fatiguing contraction, and after rest. Coherence between composite MU spike trains, derived from decomposed surface EMG, were examined in the delta (14 Hz), alpha (812 Hz), beta (1530 Hz), and gamma (3060 Hz) frequency band ranges. A significant increase in MU coherence was observed in the delta, alpha, and beta frequency bands postfatigue. In addition, wavelet coherence revealed a tendency for delta-, alpha-, and beta-band coherence to increase during the fatiguing contraction, with subjects exhibiting low initial coherence values displaying the greatest relative increase. This was accompanied by an increase in MU short-term synchronization and a decline in mean firing rate of the majority of MUs detected during the sustained contraction. A model of the motoneuron pool and surface EMG was used to investigate factors influencing the coherence estimate. Simulation results indicated that changes in motoneuron inhibition and firing rates alone could not directly account for increased beta-band coherence postfatigue. The observed increase is, therefore, more likely to arise from an increase in the strength of correlated inputs to MUs as the muscle fatigues.
Funding Details: Irish Research Council
Type of material: Journal Article
Publisher: American Psychological Society
Copyright (published version): 2016 The American Psychological Society
Keywords: Motor unit coherence;Isometric fatigue;Intramuscular coherence;Beta-band coherence;Short-term synchronization
DOI: 10.1152/jn.00097.2016
Language: en
Status of Item: Peer reviewed
Appears in Collections:Electrical and Electronic Engineering Research Collection
Insight Research Collection

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