Masaru Ueji

Influence of Grip Strength on Metacarpal Bone Mineral Density in Postmenopausal Japanese Women: A Cross-Sectional Study

Abstract. Most published studies on the role of muscle strength in the maintenance of bone mineral density (BMD) focused on the relationship between specific muscle groups and adjacent bones, mostly in young and premenopausal women. This study examined the influence of grip strength on BMD of the metacarpal index in postmenopausal Japanese women. Subjects included 1168 postmenopausal women aged 40–70 years. BMD measurement was done with computed X-ray densitometry (CXD) by analyzing X-ray films of the right second metacarpal index. Grip strength was measured in both the dominant and nondominant hands using a squeeze dynamometer. Grip strength (r = 0.2474; P= 0.0001) and age (r =−0.5443; P= 0.0001) significantly correlated positively and negatively, respectively, with BMD. Physical activity (r = 0.1318; P= 0.0001) also correlated positively with BMD. Breastfeeding (r =−0.1658; P= 0.0001), however, correlated negatively with BMD. Subjects with a history of regular physical activity had higher grip strengths and BMD, than those with no physical activity. Adjustment for age, physical activity, calcium intake, BMI, breastfeeding, testing site, and menopausal type indicated a significant (P for trend = 0.0013) positive association of grip strength with BMD. Subjects with stronger grip strengths had a decreased risk for low BMD.

Structural Equation Modeling of the Relationship of Bone Mineral Density and Its Risk Factors in Japanese Women

Several factors have been reported as risk factors for the development of osteoporosis. In this study, we aimed to examine the relationship among lifestyle factors, biologic factors, and bone mineral density (BMD) using structural equation modeling (SEM). The subjects in the present study consisted of 866 postmenopausal Japanese women aged between 40 and 80 years old. In the analysis by the SEM, we employed a multiple basic model. As the structural variables, lifestyle factors and biologic factors were selected.The goodness of fit index (GFI) of the final model was 0.991 and the Akaike’s information criteria (AIC) showed the lowest value in the peripheral models. The degree of association between biologic factors and BMD was −0.576 (direct association), 0.012 (indirect association), and −0.564 (total association). With regard to the correlation between lifestyle factors and BMD, the degrees of association were 0.085, −0.084, and 0.001, respectively.This study defined a pilot model for factors influencing BMD. Although is remains necessary to conduct further analyses with more valid measurements and constructs, this model indicated that the correlation between BMD and lifestyle factors was lower than that between BMD and biologic factors.