Role of moderate exercising on Achilles tendon collagen crimping patterns and proteoglycans

Abstract

In this study, the morphological and morphometric changes in the collagen crimping pattern of Achilles tendon and metabolism/expression of tenocytes explanted from tendons of running (RUN) and sedentary (SED) rats were investigated to assess the effects of 12 weeks moderate running exercise. The number, the top angle width and the base length of each crimp in three different regions (proximal, central and distal) of RUN and SED tendons were measured with a polarized light microscope. The most significant morphometric differences in the crimps were detectable in the central region of the RUN tendons. In this region, crimps were fewer, larger and more flattened than those of other regions as a consequence of a functional adaptation of extracellular matrix to running, in order to increase tendon stiffness and force transmission efficiency. Conversely, the top angle width of the crimps reduced in proximal and distal regions of the RUN tendons, suggesting that these crimps might act as more reactive mechanical springs, able to store and improve the release of the stored strain energy in most loaded regions. Tenocytes explanted from Achilles tendons of both RUN and SED groups were cultured. Running influenced tenocytes which showed a significant increase in collagen type-I synthesis and proteoglycans production, suggesting enhancement of the loading transmission efficiency and facilitate inter-fibril and inter-fiber sliding.

Aligned Nanofiber Topography Directs the Tenogenic Differentiation of Mesenchymal Stem Cells

“…We also found the GAG deposition to increase over time in all three groups from day 1, day 7 and day 14. An increase in proteogylcans may result in enhancement of fibril and fiber sliding, necessary for proper mechanical function of collagen in tendon [39]. These findings corroborate previous reports of elevated matrix production on nanofibers in response to both parallel and perpendicular orientation of fibers.…”

MR‐based in vivo follow‐up study of Achilles tendon volume and hydration state after ankle‐loading activity

“…() summarizes our current understanding of tendon microstructure adaptations to training and physical activity. Contrary to earlier reports, recent experimental data indicate that human tendons have the capacity to adapt relatively quickly to changing demands and that this tissue type shows a remarkably high metabolic activity (Hannukainen et al., ; Magnusson et al., ; Franchi et al., ).…”

Intensity‑dependent effect of treadmill running on rat Achilles tendon

“…Col I fibers are predominant structural components with dense, parallel arrays, and are regarded as major contributors in the transmission of mechanical force (5). The proportion and structure of collagen fibrils are crucial for the function of tendons and changes to the structure or proportion may result in adaptation or injury (6).…”