Anconeus motor unit number estimates using decomposition-based quantitative electromyography

Authors

  • Daniel E.S. Stevens BSc,

    1. Canadian Centre for Activity and Aging, School of Kinesiology, Faculty of Health Sciences, University of Western Ontario, London, Ontario, Canada
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  • Brad Harwood PhD,

    1. Canadian Centre for Activity and Aging, School of Kinesiology, Faculty of Health Sciences, University of Western Ontario, London, Ontario, Canada
    2. Department of Physiology, University of Arizona, Tucson, Arizona, USA
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  • Geoffrey A. Power PhD,

    1. Canadian Centre for Activity and Aging, School of Kinesiology, Faculty of Health Sciences, University of Western Ontario, London, Ontario, Canada
    2. Human Performance Laboratory, University of Calgary, Calgary, Alberta, Canada
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  • Timothy J. Doherty MD, PhD,

    1. Department of Physical Medicine and Rehabilitation, University of Western Ontario, London, Ontario, Canada
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  • Charles L. Rice PhD

    Corresponding author
    1. Canadian Centre for Activity and Aging, School of Kinesiology, Faculty of Health Sciences, University of Western Ontario, London, Ontario, Canada
    2. Department of Anatomy and Cell Biology, Schulich School of Medicine and Dentistry, University of Western Ontario, London, Ontario, Canada
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ABSTRACT

Introduction: Motor unit number estimates (MUNEs) provide important information in health, aging, and disease, and can be determined using decomposition-enhanced spike-triggered averaging (DE-STA). Discrimination of surface-detected motor unit potentials (S-MUPs) has been limited to contractile forces of ∽30% maximum voluntary contraction (MVC), which is insufficient to recruit a representative sample of the entire MU pool in most muscles. Unique features of the anconeus may permit MUNEs at high muscle activation levels. Methods: In 10 men (25 ± 3 years), anconeus MUNEs were performed using DE-STA at 10%, 30%, and 50% root-mean-square of MVC (RMSMVC). Results: The mean compound muscle action potential of the anconeus was ∽6 mV, and average S-MUP amplitudes were ∽100 μV, 145 μV, and 235 μV at 10%, 30%, and 50% RMSMVC, resulting in low average MUNEs of 58, 38, and 25, respectively. Conclusions: Elbow extensor force–EMG relationships suggest full recruitment of the anconeus MU pool at 50% RMSMVC, thus providing a representative sample for MUNE. Muscle Nerve 50: 52–59, 2014

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