Peak landing force as a predictor of regional proximal femur bone mineral density in physically inactive postmenopausal women

Abstract

The proximal femur is a clinically relevant site in postmenopausal skeletal health, yet the association between countermovement jump (CMJ)-derived biomechanical variables and regional proximal femur bone mineral density (BMD) remains insufficiently explored. This study examined the relationship between CMJ-derived parameters and proximal femur BMD in physically inactive postmenopausal women. 120 women were recruited, and 110 were included in the final analysis after exclusion of invalid jump trials. BMD was assessed by dual-energy X-ray absorptiometry at the femoral neck, greater trochanter, femoral shaft, and total hip. Participants performed three maximal CMJs on a force platform, from which peak landing force, flight time, jump height, and the flight-to-jump time ratio were derived. Multiple linear regression models were fitted for each DXA outcome using anthropometric covariates and CMJ-derived parameters as predictors. All models were statistically significant and explained 21%–32% of the variance in the DXA outcomes. Total hip BMD showed the best overall fit (adjusted R² = 0.32; CV-RMSE = 11%), followed by shaft BMD (adjusted R² = 0.31; CV-RMSE = 12%). Peak landing force was the CMJ-derived variable with the lowest p-value in all four models, reaching statistical significance for femoral neck, shaft, and total hip BMD, but not for trochanter BMD. These findings suggest that landing-phase mechanical characteristics may be more closely associated with proximal femur BMD than temporal CMJ variables in physically inactive postmenopausal women. Although the associations were moderate and do not support replacing DXA, they highlight the value of functional biomechanical testing in skeletal health research.