title: Motor unit number estimation and neuromuscular fidelity in 3 stages of sarcopenia.
abstract: Loss of motor units (MUs) and alterations in MU properties are major factors in development of sarcopenia. The purpose of this study was to compare MU properties among 3 groups categorized as either pre-sarcopenic (n = 7), sarcopenic (n = 7), or severely sarcopenic (n = 5), all with similarly aged subjects (75-82 years).
  
  
  
  Using decomposition-enhanced quantitative electromyography, MU number estimates and neuromuscular stability measures of near-fiber (NF) jitter and jiggle were derived in addition to contractile properties of ankle dorsiflexors.
  
  
  
  MU number estimates were similar across groups; however, maximal voluntary strength in the severe sarcopenia group was 27% and 37% less than the sarcopenic and pre-sarcopenic groups, respectively. Moreover, NF jiggle was 31% greater in the severe group compared with pre-sarcopenia, NF jitter was 43% greater in the severe group compared with the pre-sarcopenic group.
  
  
  
  Unlike MU number estimates, strength and MU stability differed across groups and related to degree of sarcopenia. Muscle Nerve 55: 676-684, 2017.
authors: School of Kinesiology, Faculty of Health Sciences, The University of Western Ontario, London, Ontario, Canada.
authors: Kevin J
authors: KJ
authors: Gilmore
authors: German Sport University Cologne, Institute of Movement and Sport Gerontology, Cologne, Germany.
authors: Tobias
authors: T
authors: Morat
authors: Department of Clinical Neurological Sciences, The University of Western Ontario, London, Ontario, Canada.|Department of Physical Medicine and Rehabilitation, The University of Western Ontario, London, Ontario, Canada.
authors: Timothy J
authors: TJ
authors: Doherty
authors: School of Kinesiology, Faculty of Health Sciences, The University of Western Ontario, London, Ontario, Canada.|Department of Anatomy and Cell Biology, Schulich School of Medicine and Dentistry, The University of Western Ontario, London, Ontario N6G 1H1, Canada.
authors: Charles L
authors: CL
authors: Rice
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000375:Aging / Q000502:physiology; D004576:Electromyography; D005260:Female; D018737:Hand Strength / Q000502:physiology; D006801:Humans; D008297:Male; D009046:Motor Neurons / Q000502:physiology*; D009119:Muscle Contraction / Q000502:physiology*; D053580:Muscle Strength / Q000502:physiology*; D018482:Muscle, Skeletal / Q000503:physiopathology*; D009469:Neuromuscular Junction / Q000503:physiopathology*; D055948:Sarcopenia / Q000503:physiopathology*
keywords: aging; electromyography; human; motor neuron; muscle; strength