title: Anconeus motor unit number estimates using decomposition-based quantitative electromyography.
abstract: BACKGROUND
  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 (RMS(MVC)).
  
  
  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% RMS(MVC), 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% RMS(MVC), thus providing a representative sample for MUNE.
authors.affiliation: Canadian Centre for Activity and Aging, School of Kinesiology, Faculty of Health Sciences, University of Western Ontario, London, Ontario, Canada.
authors.forename: Daniel E S
authors.initials: DE
authors.lastname: Stevens
authors.forename: Brad
authors.initials: B
authors.lastname: Harwood
authors.forename: Geoffrey A
authors.initials: GA
authors.lastname: Power
authors.forename: Timothy J
authors.initials: TJ
authors.lastname: Doherty
authors.forename: Charles L
authors.initials: CL
authors.lastname: Rice
mesh_terms: D000200:Action Potentials / Q000502:physiology; D000328:Adult; D002452:Cell Count; D003627:Data Interpretation, Statistical; D004550:Elbow / Q000502:physiology; D004558:Electric Stimulation; D004576:Electromyography / Q000379:methods*; D006801:Humans; D016018:Least-Squares Analysis; D008297:Male; D009046:Motor Neurons / Q000502:physiology*; D009119:Muscle Contraction / Q000502:physiology; D018485:Muscle Fibers, Skeletal / Q000502:physiology*; D018482:Muscle, Skeletal / Q000166:cytology / Q000294:innervation / Q000502:physiology*; D009462:Neurology / Q000379:methods*; D012016:Reference Values; D014159:Transducers; D055815:Young Adult
keywords: MUNE, triceps brachii; elbow extensors, EMG; force-EMG relationship