Mechanobiology of bone.

Bone is a tissue that dynamically adapts mass and architecture to the mechanical loads that occur in daily life in a world with gravity. Bone architecture and mass are influenced by the applied tension peak, whereas the bone formation rate is modulated by the stimulus frequency. In bone tissue, osteocytes govern the detection of mechanical afferents and their transformation into biochemical messages, therefore these cells can be considered a mechanosensor that directs osteogenesis to where it is most needed to increase bone strength. The stimulation of osteocytes occurs with several modalities: shear stress and stretch, extracellular pressure modifications, strains, variations of electric field in and around osteocytes lacunae. The osteocyte network, under physiological conditions, activates osteoclastogenesis and suppresses osteoblast function enhancing bone resorption and inhibiting bone formation. In the unloaded condition, the functions of the osteocyte network are augmented, whereas exercise could decrease inhibitory effects on bone mass by reducing both osteoclastogenesis and inhibition on osteoblast function.