Mechanical loading of bone during growth: lessons learned from rats and horses

Exercise when young has been shown to induce an adaptive response that may be beneficial for lifelong bone health. Using gait experiments coupled with finite element models, we sought to understand how bone accommodates the mechanical demands associated with increasing mass. We found that both murine tibiae and equine phalanx bones tend to scale for bending strength. There was an inverse relationship between structural properties and apparent mineral density in murine bone suggesting a trade-off between quantity and composition. Equine bone was optimized via increases in trabecular mineralization and cortical area. These data suggest temporal and spatially specific changes in bone mineralization and accrual rates to maintain bone strength during growth.