Association between bone-specific physical activity scores and pQCT-derived measures of bone strength and geometry in healthy young and middle-aged premenopausal women

SUMMARY: The aim of this study was to determine if bone-specific physical activity questionnaire (BPAQ) scores were positively related to bone health in healthy young and middle-aged premenopausal women. The total BPAQ was a stronger predictor of bone strength and bone mineral density of hip in young women as compared to middle-aged premenopausal women. PURPOSE: The purpose of this study was to determine whether the BPAQ scores were predictive indices of volumetric BMD (vBMD), bone strength, and bone geometry in young and middle-aged premenopausal women. METHODS: Healthy young (n = 60) and middle-aged premenopausal women (n = 54) between the ages of 18 and 50 years were recruited for this study. Areal bone mineral density (aBMD) of lumbar spine and dual proximal femur (FN; femoral neck) was measured using DXA. We assessed vBMD of the tibia 4%, 38%, and 66% by peripheral quantitative computed tomography (pQCT). The BPAQ was used to obtain a comprehensive account of lifetime physical activity related to bone health. RESULTS: Pearson’s correlation tests showed positive correlations between total BPAQ and aBMD of the right FN (r = 0.313, p = 0.015) and the left FN (r = 0.307, p = 0.017) in young women while not found in middle-aged premenopausal women (p > 0.05). A positive relationship was only observed between total BPAQ and tibia 38% vBMD in middle-aged premenopausal women (r = 0.283, p = 0.038). All bone geometry variables were associated with total BPAQ (r = 0.280–0.422, p = 0.03–0.001) in young women. The Strength-Strain Index of tibia 38% (r = 0.350, p = 0.006) and 66% (r = 0.406, p = 0.001) was associated with total BPAQ in young women. In both young and middle-aged premenopausal women, when age, bone-free lean body mass (BFLBM), and total BPAQ were included in a stepwise multiple linear regression analysis, BFLBM was a significant predictor of all aBMD variables, accounting for 7–25.7% (p = 0.043–0.001). CONCLUSIONS: The total BPAQ score-derived physical activity was more predictive of positive bone characteristics in young women than in middle-aged premenopausal women.