Muscle strength is associated with bone health independently of muscle mass in postmenopausal women: the Japanese population-based osteoporosis study.

There are conflicting reports on whether muscle strength is associated with bone mineral density (BMD) independently of muscle mass. Here, we examined the association between muscle strength and BMD in a representative population of Japanese women. Cross-sectional data from 680 postmenopausal women, who were participants in the 15th-year follow-up survey of the Japanese Population-based Osteoporosis cohort study, were analyzed. Areal BMD (aBMD) at the femoral neck and lumbar spine, whole-body bone mineral density, and appendicular skeletal muscle mass (ASM, kg) were measured by dual-energy X-ray absorptiometry. The ASM index (ASMI, kg/m2) was calculated as ASM divided by height squared (m2). Grip strength (kg) was measured as an indicator of muscle strength. Grip strength showed significantly (P < 0.05) positive relationships with aBMDs at several skeletal sites after adjusting for ASMI and age (standardized partial regression coefficient (ß) = 0.102 at femoral neck, ß = 0.126 at lumbar spine). Adjusted means of aBMD at the femoral neck and lumbar spine showed significant increasing trends from the lowest to highest tertile of grip strength. Our findings indicate that muscle strength is associated with aBMD at several sites independently of muscle mass in Japanese postmenopausal women. Thus, postmenopausal women with strong muscle strength tend to have a healthy bone status regardless of muscle size.

Low bone mineral density is associated with an elevated risk of developing increased arterial stiffness: A 10-year follow-up of Japanese women from the Japanese Population-based Osteoporosis (JPOS) cohort study.

OBJECTIVE: Only a few longitudinal studies have assessed the relationship between bone mineral density (BMD) and arteriosclerosis. This study aimed to determine whether low BMD at baseline is associated with the development of increased arterial stiffness, as evaluated by brachial-ankle pulse wave velocity (baPWV), in Japanese women. METHODS: A baPWV value of ≥1800 cm/s was adopted as the criterion for increased arterial stiffness, i.e., the outcome of the study. Of the 725 women aged ≥50 years who completed the baseline survey, we excluded the 166 who already met this criterion. Of the remaining women, we analyzed data from the 446 who completed at least one of the follow-up surveys conducted 5 or 10 years after baseline. BMD at the lumbar spine (LS) and total hip (TH) was measured by dual-energy X-ray absorptiometry in the baseline survey. baPWV was measured both at baseline and at follow-up. Multivariate logistic regression was used to evaluate the independent effect of BMD at baseline on developing the outcome during 10-year follow-up. RESULTS: We identified 166 women who newly developed increased arterial stiffness. The odds ratios (OR) for a 1 SD decrease in BMD at LS and TH for developing the outcome were 1.20 (95% confidence interval [CI]: 0.91-1.50), and 1.44 (95% CI: 1.14-1.81), respectively, after adjusting for age and systolic blood pressure. After additionally adjusting for baPWV at baseline, the OR for a 1 SD decrease in BMD at TH remained significant (1.33, 95% CI: 1.02-1.72). CONCLUSION: Low BMD at TH was significantly associated with the development of increased arterial stiffness during a 10-year follow-up of Japanese women.

Relative Importance of Central and Peripheral Adiposities on Cardiometabolic Variables in Females: A Japanese Population-Based Study.

In epidemiological studies, there is little evidence regarding the relative impact of central adiposity and peripheral adiposity on cardiometabolic risk factors, especially in Asian populations. This study investigated associations between central-to-peripheral fat ratios and cardiometabolic variables using data from a population-based study of Japanese women. The source population was composed of 1800 women aged 50 yr or older at the 15th- to 16th-yr follow-up survey of the Japanese Population-Based Osteoporosis Cohort Study. This study analyzed cross-sectional data from 998 women for whom complete information about body fat variables according to dual-energy X-ray absorptiometry, cardiometabolic variables, and potential confounding factors was available. Both before and after adjusting for potential confounding factors, trunk-to-appendicular fat ratios showed significant (p < 0.05) correlations with brachial-ankle pulse wave velocity, serum lipids, and hemoglobin A1c levels. Relationships between fat ratios and cardiometabolic variables were independent of relationships between fat volumes (in whole body or in trunk) and cardiometabolic variables. Furthermore, relationships between trunk-to-appendicular fat ratios and cardiometabolic variables were observed among women in the lowest tertile of total body fat (brachial-ankle pulse wave velocity, ß = 0.08; high-density lipoprotein cholesterol, ß = -0.32; low-density lipoprotein cholesterol, ß = 0.15; and hemoglobin A1C, ß = 0.16; p < 0.05, respectively). Central adiposity is more related to cardiometabolic variables than peripheral adiposity. Information on central-to-peripheral fat ratios is particularly valuable for the evaluation of relatively thin Japanese women.

Trabecular bone score (TBS) predicts vertebral fractures in Japanese women over 10 years independently of bone density and prevalent vertebral deformity: the Japanese Population-Based Osteoporosis (JPOS) cohort study.

Bone strength is predominantly determined by bone density, but bone microarchitecture also plays an important role. We examined whether trabecular bone score (TBS) predicts the risk of vertebral fractures in a Japanese female cohort. Of 1950 randomly selected women aged 15 to 79 years, we analyzed data from 665 women aged 50 years and older, who completed the baseline study and at least one follow-up survey over 10 years, and who had no conditions affecting bone metabolism. Each survey included spinal imaging by dual-energy X-ray absorptiometry (DXA) for vertebral fracture assessment and spine areal bone mineral density (aBMD) measurement. TBS was obtained from spine DXA scans archived in the baseline study. Incident vertebral fracture was determined when vertebral height was reduced by 20% or more and satisfied McCloskey-Kanis criteria or Genant's grade 2 fracture at follow-up. Among eligible women (mean age 64.1 ± 8.1 years), 92 suffered incident vertebral fractures (16.7/10(3) person-years). These women were older with lower aBMD and TBS values relative to those without fractures. The unadjusted odds ratio of vertebral fractures for one standard deviation decrease in TBS was 1.98 (95% confidence interval [CI] 1.56, 2.51) and remained significant (1.64, 95% CI 1.25, 2.15) after adjusting for aBMD. The area under the receiver operating characteristic curve of TBS and aBMD combined was 0.700 for vertebral fracture prediction and was not significantly greater than that of aBMD alone (0.673). However, reclassification improvement measures indicated that TBS and aBMD combined significantly improved risk prediction accuracy compared with aBMD alone. Further inclusion of age and prevalent vertebral deformity in the model improved vertebral fracture prediction, and TBS remained significant in the model. Thus, lower TBS was associated with higher risk of vertebral fracture over 10 years independently of aBMD and clinical risk factors including prevalent vertebral deformity. TBS could effectively improve fracture risk assessment in clinical settings.