Acute changes in knee-extensors torque, fiber pennation, and tendon characteristics.
Pearson, S and Onambele, GNL 2005, 'Acute changes in knee-extensors torque, fiber pennation, and tendon characteristics.' , Chronobiology International, 22 (6) , pp. 1013-1027.Full text not available from this repository.
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*
|Themes:||Subjects / Themes > R Medicine > R Medicine (General)
Health and Wellbeing
|Schools:||Schools > School of Health Sciences > Centre for Health Sciences Research
Schools > School of Environment and Life Sciences
|Journal or Publication Title:||Chronobiology International|
|Publisher:||Taylor & Francis|
|Depositing User:||H Kenna|
|Date Deposited:||09 Aug 2007 13:55|
|Last Modified:||01 Dec 2015 00:01|
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