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Published on: August 14, 2021
Effect of very old age on anconeus motor unit loss and compensatory remodelling
Kevin J Gilmore1, Eric A Kirk1, Timothy J Doherty2,3
1School of Kinesiology, Canadian Centre for Activity and Aging, Faculty of Health Sciences, The University of Western Ontario, 1490 Richmond Street London, Ontario, Canada, N6G 2M3.
Introduction:
It is not known how the process of compensatory remodeling through collateral reinnervation continues into very old age (>80 years) or whether there is a limit to effective motor unit (MU) reinnervation. Therefore, we explore electrophysiological properties related to motor unit number estimates (MUNEs) in very old participants (79-90 years of age) compared with young controls (25-29 years of age).
Methods:
Decomposition-enhanced spike-triggered averaging was used to collect surface and intramuscular electromyography information from the anconeus to derive a MUNE.
Results:
Young participants had a MUNE of ∼38 and ∼25 at 30% and 50% root mean squared maximum voluntary contraction (RMSMVC ) with surface motor unit potentials (S-MUPs) of ∼145 μV and 236 μV, respectively. Older participants had a MUNE of ∼23 and ∼16 at 30% and 50% RMSMVC with S-MUPs of 168 μV and 232 μV, respectively.
Discussion:
In this muscle, an age limit to successful remodeling through collateral reinnervation, to compensate for the presumed ongoing losses of MUs, may have been surpassed. Muscle Nerve 57: 659-663, 2018.
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