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, Jason M. DeFreitas

Research output: Contribution to journalArticlepeer-review

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; RTD50) and normalized surface electromyography (first 50 ms of muscle excitation; nEMG50) were recorded from the right quadricep muscle group. MUNE was examined from the right vastus lateralis. Multiple linear regression analyses revealed that nEMG50 had a significant effect on RTD50 independent of age group (p ≤ 0.001). nEMG50 had a significant effect on RTD50 in the OM group (p = 0.037). MUNE had no effect on RTD50 independent of age. Older adults may depend more on muscle activation at contraction onset of early phase RTD compared to younger adults.

Original languageEnglish (US)
JournalJournal of Motor Behavior
DOIs
StateAccepted/In press - 2021

All Science Journal Classification (ASJC) codes

  • Biophysics
  • Orthopedics and Sports Medicine
  • Experimental and Cognitive Psychology
  • Cognitive Neuroscience

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