Investigating the Effects of Age and Sex on Musculotendinous Stiffness at the Vastus Lateralis Muscle
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Date
2024
Authors
Choi, Hye Lynn
Journal Title
Journal ISSN
Volume Title
Publisher
University of Oregon
Abstract
The purpose of this study was to investigate how biological sex and chronological age influence the mechanical stiffness in muscle tissue and the response of that tissue to an acute bout of fatiguing exercise. Stiffness in the vastus lateralis (VL) muscle was measured in young (18-35 years) and older (65 to 80 years) males and females. This project tested the hypothesis that older individuals will have lower stiffness than younger individuals, and the female subjects will have lower stiffness values than male subjects. Participants were young females (n=6) and males (n=4), and older females (n=5), and males (3). Dynamometry was used to measure rate of torque development and other measures of voluntary contractile performance. Shear wave elastography (SWE) ultrasonography was used to measure stiffness in VL muscle tissue. These were complimented by more traditional B-mode ultrasound measures of stiffness and morphology (echogenicity). SWE measures were applied during passive and active contraction of the VL. B-mode ultrasound was applied during VL contractions of progressively greater intensity. Age-related reductions in VL stiffness were limited to males measured with SWE. The female group did not report a similar result, suggesting that the age-interaction effect may be specific to a certain sex. Echogenicity was significantly correlated with peak power, absolute and relative rate of torque development (p<0.05). The finding suggests that the age-effect on the stiffness at the vastus lateralis muscle may be sex-specific to males. Muscle composition as defined by echogenicity may be a more highly relevant clinical measure.
Description
34 pages
Keywords
Human Physiology, Anatomy, Muscle, Stiffness, Aging