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The Influence of Motor Unit Number and Muscle Activation on Early Phase Rate of Torque Development in Younger and Older Men
Journal article   Peer reviewed

The Influence of Motor Unit Number and Muscle Activation on Early Phase Rate of Torque Development in Younger and Older Men

Mitchel A. Magrini, Ryan J. Colquhoun, Matt C. Ferrell, Sydnie R. Fleming, Jacob A. Mota, Jacob A. Siedlik, Nick M. Poidomani, Nathaniel D.M Jenkins and Jason M. DeFreitas
Journal of motor behavior, Vol.54(4), pp.422-428
06/13/2022
PMID: 34763617
Web of Science ID: WOS:000717357700001

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Abstract

This study examined the influence of muscle activation and motor unit number estimation (MUNE) on early phase voluntary rate of torque development (RTD) in younger (YM) and older (OM) men. Thirty-two YM (n = 17; Age = 22 yrs) and OM (n = 15; Age = 74 yrs) volunteered to participate in this study. Early phase RTD (first 50 ms of a rapid isometric contraction; RTD 50 ) and normalized surface electromyography (first 50 ms of muscle excitation; nEMG 50 ) were recorded from the right quadricep muscle group. MUNE was examined from the right vastus lateralis. Multiple linear regression analyses revealed that nEMG 50 had a significant effect on RTD 50 independent of age group (p ≤ 0.001). nEMG 50 had a significant effect on RTD 50 in the OM group (p = 0.037). MUNE had no effect on RTD 50 independent of age. Older adults may depend more on muscle activation at contraction onset of early phase RTD compared to younger adults.

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