Acute changes in knee-extensors torque, fiber pennation, and tendon characteristics.

Pearson, S ORCID: and Onambele, GNL 2005, 'Acute changes in knee-extensors torque, fiber pennation, and tendon characteristics.' , Chronobiology International, 22 (6) , pp. 1013-1027.

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The aim of the current study was to examine the relationships between quadriceps torque, vastus lateralis pennation angle (theta), and patella tendon stiffness (K) at 07:45 and 17:45 h. Using short-duration static contractions, simultaneous recordings were made of vastus lateralis (VL) electromyograph (EMG), theta and patella tendon K. Peak isometric extension torque (Peak torque Ext(corr)) increased by 29.4±6.5% at a knee angle of 70 degrees (p=0.03) in the evening compared to the morning. In the contracted muscle, a 35.0±11.0% (p=0.02) time-of-day (TOD)-related change in theta (to a greater evening compared to morning theta) was observed. Morning and evening measures of theta were also made, both at rest and at a standardized force level (250 N), to separate architecture change effects from increased torque capacity effects. Significant increments in theta in both the resting muscle (13.0±5.1%, p=0.046) and during the standardized exertions (8.0±3.1%, p=0.04) were observed in the evening versus the morning. Increases in theta with TOD were significantly correlated with the 40% (p=0.018) decrease in K both during the standardized contractions (r=0.788, p < 0.001) and at rest (r=0.77, p=0.026). These data show that TOD affects K and theta and that these two important factors involved in in-vivo muscle torque generation capacity are associated. The data also show that despite the potentially deleterious effects of the direction of the changes in both K and theta with TOD, peak torque Ext(corr) still shows a significant upward shift in the evening relative to the morning. MeSH Terms: * Adult * Circadian Rhythm* * Electromyography * Humans * Knee Joint/physiology* * Male * Muscle Contraction/physiology * Muscle Fibers/physiology* * Muscle, Skeletal/anatomy & histology * Muscle, Skeletal/physiology * Patella/anatomy & histology * Patella/physiology * Tendons/physiology* * Torque*

Item Type: Article
Themes: Subjects / Themes > R Medicine > R Medicine (General)
Health and Wellbeing
Schools: Schools > School of Environment and Life Sciences
Schools > School of Health and Society > Centre for Health Sciences Research
Journal or Publication Title: Chronobiology International
Publisher: Taylor & Francis
Refereed: Yes
ISSN: 1525-6073
Depositing User: H Kenna
Date Deposited: 09 Aug 2007 13:55
Last Modified: 27 Aug 2021 21:59

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