Examining motor unit discharge properties during dynamic muscle actions in males and females
Citations
Altmetric:
Soloist
Composer
Publisher
Date
2025-05-04
Additional date(s)
Abstract
Motor unit firing behavior is influenced by task demands and sex differences. This study compares motor unit population firing behavior of the biceps brachii between two dynamic muscle action intensities (~90% and ~98% 1RM). Using surface EMG decomposition, we analyzed the average motor unit action potential amplitude (MUAPamp) and firing rate (FR) relationship, identifying the Y-intercepts and slopes. A total of 1,361 motor units were identified across loading conditions. Our results indicate that Y-intercept, but not slope, increases with load. Notably, females exhibited significantly lower Y-intercepts, FR, MUAPamp, and slopes (steeper) than males. These findings suggest that, during these conditions, motor unit populations adapt their discharge properties in a load-dependent manner. The observed sex-dependent differences are likely attributed to variations in muscle fiber composition and neural control strategies. These findings provide novel evidence of load-dependent motor unit firing behavior and divergent firing characteristics between sexes during maximal-intent dynamic muscle actions.
Contents
Subject(s)
Research Projects
Organizational Units
Journal Issue
Genre
Thesis
Description
Format
Department
Kinesiology
Advisor
Carr, Joshua C.
Weyand, Peter
Weyand, Peter