Eccentric Countermovement Jump Mechanics Are Associated with Bone Properties in Physically Inactive Early...

Countermovement jump (CMJ) assessment is widely used to evaluate lower-body neuromuscular performance, but its potential relationship with bone health remains insufficiently understood. This study aimed to determine whether eccentric-phase force-time characteristics during the CMJ are associated with proximal femur bone density, mass, and structural properties in postmenopausal women. One hundred and ten physically inactive women within 10 years after menopause underwent bone and jump assessments. Areal bone mineral density and bone mineral content were measured using dual-energy X-ray absorptiometry, and three-dimensional cortical and trabecular proximal femur parameters were estimated from dual-energy X-ray absorptiometry images. Participants performed maximal countermovement jumps on a force platform. Seventeen eccentric-phase force-time variables were extracted and reduced using principal component analysis. Multivariable linear regression models adjusted for age, body mass, height, waist circumference, and hip circumference examined associations between eccentric mechanical profiles and bone outcomes. Four principal components explained 90.5% of the variance in eccentric jump mechanics. Regression models explained between 11% and 41% of the variance across bone outcomes, with the strongest models observed for trabecular bone mineral content at the femoral neck (R² = 0.41), bone mineral content at the femoral shaft (R² = 0.40), and total trabecular volume (R² = 0.39). The component reflecting greater countermovement depth and longer eccentric duration showed the most consistent contribution across models, whereas the force-power component contributed to selected trabecular outcomes. These findings suggest that the combined eccentric mechanical profile of the CMJ is associated with proximal femur bone properties in physically inactive women in early postmenopause and may help inform the biomechanical assessment of bone health and the development of bone-targeted exercise interventions in this population.