Sex differences in laterality of motor unit firing behavior of the first dorsal interosseous muscle in strength-matched healthy young males and females. Eur J Appl Physiol 2024 Jul;124(7):1979-1990
Date
02/17/2024Pubmed ID
38366213Pubmed Central ID
PMC11199256DOI
10.1007/s00421-024-05420-7Scopus ID
2-s2.0-85185149057 (requires institutional sign-in at Scopus site) 3 CitationsAbstract
PURPOSE: The purpose of this study was to compare laterality in motor unit firing behavior between females and males.
METHODS: Twenty-seven subjects (14 females) were recruited for this study. The participants performed ramp up and hold isometric index finger abduction at 10, 30, and 60% of their maximum voluntary contraction (MVC). High-density surface electromyography (HD-sEMG) signals were recorded in the first dorsal interosseous (FDI) muscle and decomposed into individual motor unit (MU) firing behavior using a convolution blind source separation method.
RESULTS: In total, 769 MUs were detected (females, n = 318 and males, n = 451). Females had a significantly higher discharge rate than males at each relative torque level (10%: male dominant hand, 13.4 ± 2.7 pps vs. female dominant hand, 16.3 ± 3.4 pps; 30%: male dominant hand, 16.1 ± 3.9 pps vs. female dominant hand, 20.0 ± 5.0 pps; and 60%: male dominant hand, 19.3 ± 3.8 vs. female dominant hand, 25.3 ± 4.8 pps; p < 0.0001). The recruitment threshold was also significantly higher in females than in males at 30 and 60% MVC. Furthermore, males exhibited asymmetrical discharge rates at 30 and 60% MVC and recruitment thresholds at 30 and 60% MVC, whereas no asymmetry was observed in females.
CONCLUSION: In the FDI muscle, compared to males, females exhibited different neuromuscular strategies with higher discharge rates and recruitment thresholds and no asymmetrical MU firing behavior. Notably, the findings that sex differences in neuromuscular activity also occur in healthy individuals provide important information for understanding the pathogenesis of various diseases.
Author List
Nishikawa Y, Watanabe K, Holobar A, Kitamura R, Maeda N, Hyngstrom ASAuthor
Allison Hyngstrom PhD Associate Professor in the Physical Therapy department at Marquette UniversityMESH terms used to index this publication - Major topics in bold
AdultElectromyography
Female
Functional Laterality
Humans
Isometric Contraction
Male
Motor Neurons
Muscle Contraction
Muscle, Skeletal
Recruitment, Neurophysiological
Sex Characteristics
Young Adult