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

Pearson, S; Onambele, GNL

Abstract

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*

Citation

Pearson, S., & Onambele, G. (2005). Acute changes in knee-extensors torque, fiber pennation, and tendon characteristics. Chronobiology International, 22(6), 1013-1027. https://doi.org/10.1080/07420520500397900

• Journal Article Type: Article
• Publication Date: Dec 1, 2005
• Deposit Date: Aug 9, 2007
• Journal: Chronobiology International
• Print ISSN: 0742-0528
• Publisher: Taylor and Francis
• Peer Reviewed: Peer Reviewed
• Volume: 22
• Issue: 6
• Pages: 1013-1027
• DOI: https://doi.org/10.1080/07420520500397900