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

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.