INTRODUCTION: Acute and chronic injuries both in alpine skiing and other sports often affect the connective tissue in the form of acute rupture of ligaments or tendons, or overuse injury of the tendon tissue. Rather that being an inert tissue, the connective tissue reveals a dynamic adaptation to loading in its protein components. Collagen formation as well as collagen degradation in the tendon rises with both acute and chronic loading, and every bout of exercise elevates collagen formation for 2-3 days. Thus connective tissue can easily be trained with resting days in between. Data suggests that a gender difference exists with regards to tendon adaptation to exercise, in that females respond less than males with regards to a rise in collagen formation after exercise. It is suggested that estrogen may contribute to a diminished collagen synthesis response in females, and maybe the effect is exerted via Insulin like growth factor.l (IGF-1). Conversely, the Stimulation of collagen synthesis by other growth factors can be shown in both animal and human models where IGF-1 and transforming growth factor beta1 (TGF-b1) expression increases accompanying or preceding a rise in procollagen expression and collagen synthesis. In humans it can be demonstrated that a rise in release and interstitial concentration of TGF-beta, Prostaglandin E2, IGF-1 binding proteins and interleukin 6 takes place after exercise. Clinically tendon overuse injuries are treated with controlled strength training of muscle and tendon tissue. The rise in IGF-1 and procollagen expression showed similar response whether the tendon was stimulated by concentric, isometric or eccentric muscle contraction, suggesting that strain rather that stress/torque determines the collagen synthesis stimulating response seen with exercise. Administration of growth hormone (GH) resulted in increased expression of IGF-1 and collagen in tendon tissue. The adaptation time to chronic loading is longer in tendon tissue compared to contractile elements of skeletal muscle or heart, and only with very prolonged loading, significant changes in gross dimensions of the tendon are observed. However, the influence of pharmacological agents on tendon structure occurs all the way down to the molecular level, and can influence inter-molecular and inter-fibrillar cross bindings. Recovery after injury in tendon is associated with increased collagen synthesis and angiogenesis that remains upregulated up to 2 years after the injury. Current observations support the notion that mechanical loading leads to collagen rich tissue adaptation, and that this requires an intimate interplay between mechanical signalling and biochemical changes in the matrix, such that Chemical changes can be converted into adaptations in morphology, structure and material properties. So, although excessive loading can lead to overuse injury of tendon, loading is also the prerequisite to maintain the fibroblasts of tendon tissue active in order to provide optimal collagen formation and result in the most load-resistant structures that can resist loading during skiing and thus avoid injuries.
© Copyright 2007 4th International Congress on Science and Skiing. Julkaistu Tekijä University of Salzburg. Kaikki oikeudet pidätetään. / Kääntänyt https://www.DeepL.com/Translator