Fig. 1.

Physical activity exerts forces on bone at multiple length scales. Bone matrix is subjected simultaneously to numerous mechanical forces during physical activity including strains, accelerations, and fluid shear stress. These tissue level forces are transduced to various cell populations in bone, including osteoblasts, osteocytes, osteoclasts, adipocytes and mesenchymal stem cells, and provide a basis of mechano-regulation of bone at the cellular level.