Tendon biomechanics

Tendon connective tissue adapts to mechanical loading with increased synthesis and turnover of matrix proteins. Collagen formation and degradation increase with acute loading of tendon and skeletal muscle, and this is associated with local and systemic release of growth factors (e.g. IGF-1, TGF-beta). Chronic loading of tissue, such as with physical training, leads to increased collagen turnover and a net collagen synthesis together with a modification of the mechanical properties of the tendon, including a reduction in tendon stress. The adaptation time to chronic loading is longer in tendon tissue than in contractile elements of skeletal muscle or heart, and only very prolonged loading will significantly change gross dimensions of the tendon. Mechanical signalling in the tissue leads to biochemical changes in the matrix that can be converted into adaptations in morphology, structure and biomechanical properties of the tendon.