Skeletal Muscle Compliance and Composition in Resistance Trained and Non-Trained Men
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Date
2022
Authors
Donovan, Allen
Journal Title
Journal ISSN
Volume Title
Publisher
University of Oregon
Abstract
Skeletal muscle structure and function are inextricably bound as the mechanics of force generation and transmission are linked by the structures that connect muscle proteins to bone. Muscle force generating capacity is commonly cited as the hallmark of muscle function, but musculotendinous stiffness, at the whole muscle level, is an aspect of muscle that can either enhance or diminish performance. Purpose: The purpose of this study is to identify and understand musculotendinous properties in young adult males and compare those results to the musculotendinous properties in young adult women while providing further justification for the use of digital palpation in clinical settings. Therefore, our primary hypothesis is that activity will do more to affect stiffness than biological sex. The effect of stiffness on rate of torque development was evaluated as a determiner of performance between trained and untrained individuals. Methods: In the present study, resistance trained (RT) young men (n = 8) and non- trained (NT) young males (n = 3) were recruited. B-mode ultrasonography (US) was used to measure muscle composition and thickness. Active stiffness at the patellar tendon (PT) and vastus lateralis (VL) was measured during active contraction with US and digital palpation. Digital palpation was only used for passive stiffness measurements. Results: RT men displayed a greater passive stiffness at the VL (p = .01) and visually displayed greater passive stiffness at the PT but did not portray statistical significance (p = .07). Additionally, active stiffness in the VL (p = .61) and PT (p = .78) were not different between groups. Absolute rate of torque development also showed no significant increase in the RT group (p = .94). Each volunteer’s rate of torque development was then fitted to their personal maximum voluntary isometric contractions (MVIC). With this adjustment, RT individuals presented a decrease in their rate of torque development (RTD) but there was still no significance (p = .19). Conclusion: Activity does not do more than biological sex to affect stiffness. Overall, this study shows that the contributions to muscle performance is complex and cannot be limited to a single variable.
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Keywords
Stiffness, Resistance Training, Skeletal Muscle, Biological Sex, Composition