Associations of Habitual Skeletal Loading with Bone Changes during the Menopausal Transition: A Follow-Up Study.

Abstract

Purpose: While weight-bearing physical activity benefits bone health, it remains unclear whether physical activity can counteract hormone-driven menopausal bone deterioration. This secondary analysis of a population-based prospective follow-up study examined changes in bone health indicators around menopause and evaluated whether accelerometer-measured habitual skeletal loading is associated with these changes.

Methods: A total of 189 initially perimenopausal women without estrogen therapy (mean age, 52 yr; SD, 2 yr) were followed until they became postmenopausal (mean follow-up time, 15 months; SD, 9 months). Femoral neck bone mineral density (FN BMD) and bone mineral content were measured with dual x-ray absorptiometry. Femoral and tibial shaft volumetric BMD (vBMD), cross-sectional geometry, and stress-strain index (SSI) were assessed using quantitative computed tomography in a subset of 61 women. Habitual skeletal loads (mean daily osteogenic index and low-, medium-, and high-intensity impact counts) were evaluated with multiple-day free-living accelerometry records. Longitudinal associations of habitual skeletal loads and bone outcomes were analyzed with generalized estimating equation models.

Results: Consistent decreases were observed in FN BMD and bone mineral content, and femoral and tibial shaft vBMD and SSI ( P < 0.001) over the follow-up. Slight decreases over the follow-up were also observed in osteogenic index and medium impacts in the full sample, and medium and high impact counts in the subsample ( P < 0.05). Medium impacts were associated with tibial shaft vBMD and SSI (β = 0.204; 95% confidence interval [95% CI], 0.018-0.391 and β = 0.077; 95% CI, 0.000-0.154, respectively). High impacts were associated with femoral shaft vBMD (β = 0.186; 95% CI, 0.006-0.366). However, no association was observed between habitual skeletal loads and changes in bone characteristics over the follow-up.

Conclusions: We observed a rather uniform skeletal response to the menopausal transition at all measured bone sites. Positive associations were found between medium and high-intensity impacts and bone characteristics at the femoral and tibial shafts. However, habitual skeletal loading did not seem to counteract bone deterioration during the menopausal transition.