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Tendon Contraction After Cyclic Elongation Is an Age-Dependent Phenomenon: In Vitro and In Vivo Comparisons
Michael Lavagnino1, Asheesh Bedi2, Christopher P Walsh2
1Laboratory for Comparative Orthopaedic Research, College of Veterinary Medicine, Michigan State University, East Lansing, Michigan, USA.
The American Journal of Sports Medicine
|March 27, 2014
Summary
Tendons elongate after cyclic loading and partially recover length over time. This tendon contraction is age-dependent, with younger tendons recovering more, potentially influencing tendinopathy risk.
Area of Science:
- Biomechanical Engineering
- Cell Biology
- Sports Medicine
Background:
- Tendons are viscoelastic tissues that elongate under cyclic loading.
- The capacity of tendons to recover this elongation is not well understood.
Purpose of the Study:
- To investigate the age-dependent recovery of tendon length after cyclic loading.
- To determine if tendon contraction after loading is cell-mediated and influenced by age.
Main Methods:
- In vitro: Rat tail tendon fascicles (RTTfs) from rats of different ages underwent cyclic strain.
- In vivo: Human participants underwent eccentric quadriceps loading, with patellar tendon length measured via radiographs before, after, and 24 hours post-exercise.
Main Results:
- Cyclic loading increased tendon length in both in vitro and in vivo models.
- Tendons showed partial, age-dependent contraction over 24 hours, with younger tendons recovering more.
- Younger rats' RTTfs contracted faster and more completely than older rats'.
Conclusions:
- Cyclic loading causes significant tendon elongation, followed by incomplete, age-dependent contraction.
- This age-related recovery pattern may impact the cellular environment and contribute to tendinopathy pathogenesis.
- Adequate recovery time between loading bouts is crucial, and age is a significant factor in tendinopathy risk.
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