Motor unit number estimation and neuromuscular fidelity in 3 stages of sarcopenia |
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| Authors: | Timothy J. Doherty MD PhD Charles L. Rice PhD |
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| Affiliation: | 1. Department of Clinical Neurological Sciences, The University of Western Ontario, London, Ontario, Canada;2. Department of Physical Medicine and Rehabilitation, The University of Western Ontario, London, Ontario, Canada;3. School of Kinesiology, Faculty of Health Sciences, The University of Western Ontario, London, Ontario, Canada;4. Department of Anatomy and Cell Biology, Schulich School of Medicine and Dentistry, The University of Western Ontario, London, Ontario N6G 1H1, Canada |
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| Abstract: | Introduction: 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). Methods: 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. Results: 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. Conclusion: Unlike MU number estimates, strength and MU stability differed across groups and related to degree of sarcopenia. Muscle Nerve 55: 676–684, 2017 |
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| Keywords: | aging electromyography human muscle motor neuron strength |
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