Influence of Muscle on Lower Limb Bone Mineral Density and Ground Reaction Force in Distance Runners

This study investigated the association between ground reaction force (GRF) characteristics and bone mineral density (BMD) and between leg muscle characteristics and BMD in runners. We also explored the effect of muscle function on the relationship between GRF and BMD. 40 runners underwent dual x-ray absorptiometry (DXA) to calculate BMD and lean mass. Dynamometry tested knee extensor and ankle plantar flexor strength. A force-instrumented treadmill measured GRF outcomes. Pearson correlation examined associations between GRF and BMD, and muscle characteristics and BMD separately by sex. Generally, higher GRF outcomes were associated with higher BMD outcomes, but only in males. Greater lean mass, but not strength, was associated with higher BMD in both sexes. Multiple regression indicated that vGRF was positively associated with shank lean mass, but only in the presence of high shank lean mass. Runners may benefit from increasing shank lean mass to facilitate the relationship between loading and BMD.