Determinants of bone health in elderly Japanese men: study design and key findings of the Fujiwara-kyo Osteoporosis Risk in Men (FORMEN) cohort study

BACKGROUND@#The Fujiwara-kyo Osteoporosis Risk in Men (FORMEN) study was launched to investigate risk factors for osteoporotic fractures, interactions of osteoporosis with other non-communicable chronic diseases, and effects of fracture on QOL and mortality.@*METHODS@#FORMEN baseline study participants (in 2007 and 2008) included 2012 community-dwelling men (aged 65-93 years) in Nara prefecture, Japan. Clinical follow-up surveys were conducted 5 and 10 years after the baseline survey, and 1539 and 906 men completed them, respectively. Supplemental mail, telephone, and visit surveys were conducted with non-participants to obtain outcome information. Survival and fracture outcomes were determined for 2006 men, with 566 deaths identified and 1233 men remaining in the cohort at 10-year follow-up.@*COMMENTS@#The baseline survey covered a wide range of bone health-related indices including bone mineral density, trabecular microarchitecture assessment, vertebral imaging for detecting vertebral fractures, and biochemical markers of bone turnover, as well as comprehensive geriatric assessment items. Follow-up surveys were conducted to obtain outcomes including osteoporotic fracture, cardiovascular diseases, initiation of long-term care, and mortality. A complete list of publications relating to the FORMEN study can be found at https://www.med.kindai.ac.jp/pubheal/FORMEN/Publications.html .

INFLUENCE OF ANTHROPOMETRIC MEASURES AND LIFESTYLE-RELATED FACTORS ON THE TWO-YEAR CHANGES OF BONE MASS IN COLLEGE-AGED WOMEN / 体力科学

The college years are an opportune timepoint of intervention in the primary prevention of osteoporosis. However, the effects of anthropometrical measures and lifestyle-related factors on the changes in bone mass during college years are unclear. The purpose of this study was thus to identify the determinants of the changes in calcaneal quantitative ultrasound (QUS) bone parameters (stiffness index: SI, speed of sound: SOS, broadband ultrasound attenuation: BUA) over 2 years in healthy Japanese college women (n=128). Correlation analysis revealed several significant relationships between the change rates in QUS parameters and anthropometry. Particularly, the changes in SI and BUA are highly correlated with the 2-year change in lean body mass (LBM). The subsequent multiple liner regression analysis also supported that the change in LBM was the significant predictor for the incremental rate of SI and BUA. All subjects then categorized into some grades, concerning about following lifestyle-related and physical variables during the last 2 years, living condition, sleeping time, alcohol consumption, smoking, meal skipping, dairy foods intake, instant foods intake, regular physical activity, regularity of menstruation, history of fracture, and history of dieting to reduce body weight. The incremental rates of all QUS parameters (i. e., SI, SOS, BUA) were positively associated with participation in regular physical activity. In addition, women who have continuously participated in regular physical activity from high school to college showed significant increases in SI and SOS compared with those who are not physically active or whose level of physical activity decline during college years. In conclusion, our study indicates that changes in QUS parameters in college-aged women were influenced by changes in anthropometric measures, especially LBM. It might suggest the importance of participation in regular physical activity to increase skeletal muscle mass. Our results also support the view that college women should maintain or increase regular physical activity before and after entering the college to maximize peak bone mass or lessen the age-related loss in bone mass in adulthood.

EFFECTS OF PROLONGED VOLUNTARY WHEEL-RUNNING ON TIBIAL BONE-MASS IN GROWING MALE RATS USING pQCT / 体力科学

In this study, we investigated the effects of prolonged voluntary running training on bone mass in the tiba of growing male SD rats. At 5 weeks old, the rats were divided into 4 groups : group 15 VE (n=7) exercised voluntarily on a running wheel for 10 weeks from 5- to 15-weeks old ; group 35 VE (n=7) exercised voluntarily on a running wheel for 30 weeks from 5- to 35-weeks old ; in groups 15SC (n=6) and 35 SC (n=5), rats were housed individually in normal plastic cages for the same periods as groups 15 VE and 35 VE, respectively. At the end of each experimental period, the right tibia from each rat was used for bone- mass analysis using peripheral quantitative cumputed tomography (pQCT) . The evaluated portions were the proximal methaphysis and the diaphysis, with total, cortical, and trabecular data from these portions being obtained as volumetric bone mineral content (vBMC) and volumetric bone mineral density (vBMD) . The results indicated that 1) although voluntary running distance tended to decline during the later period (1635 wk old) in 35 VE rats, some mean values obtained for bone mass parameters using pQCT were significant greater in 35 VE than in 35SC ; 2) the mean values from those parameters in 15 VE were not significantly different from those in 15 SC. These results suggest that the continuation of voluntary exercise may be important for bone- mass enhancement in rat tibia.

THE RELATIONSHIP BETWEEN CALCANEAL QUANTITATIVE ULTRASOUND PARAMETERS AND ANTHROPOMETRIC MEASURES IN UNIVERSITY WOMEN / 体力科学

The purpose of this study was to examine the effects of anthropometric measures, including body height, body weight, body mass index (BMI), fat mass (FM), and lean body mass (LBM), on quantitative ultrasound (QUS) parameters of calcaneus in 358 Japanese university women. Ultrasonic bone densitometer (Achilles, Lunar corp.) was utilized to measure broadband ultrasound attenuation (BUA), speed of sound (SOS), and stiffness index (SI) of the right calcaneus. The average of SI in this study showed a slight lower value (84, 3±12.1, mean±SD) compared with that in age-matched university women as previously reported. The contradictive finding may suggest the need for a large-scale further investigation on SI in young women. Correlation analysis revealed that both BUA and SI are significantly correlated with all anthropometric measures. However SOS had only weak correlation with LBM. In consideration of the high colinearities of body weight and BMI with FM and LBM, the multiple liner regression analysis was conducted with BUA, SOS, and SI as dependent variables. Body height, FM, and LBM were then entered to a forward stepwise regression model. The analysis proved that the significant predictor of BUA, SOS, and SI is LBM. It also suggested BUA to be stronger correlated with LBM than the other QUS parameters, SOS and SI. In conclusion, our re sults support the view that QUS parameters appear to be influenced by anthropometric measures, especially by LBM in Japanese university women. It is conceivable that an increase in skeletal mus cle mass chiefly induced by physical exercise contributes to the improvement of bone mass as measured by QUS in young women.

The Influence of Walking in Relation to Bone with VDR Genotypes / 体力科学

The purpose of this study was to clarify the interaction between environmental and genetic factors on bone. Using an ultrasound bone densitometer, the stiffness of calcaneus was measured in 52 postmenopausal Japanese women. The VDR gene polymorphism was defined by PCR-RFLP using the endonuclease BsmI. Daily walking steps as a physical activity was measured in these subjects with a pedometer for 7 days and calculated as walking steps per day. Simple regression analysis showed that stiffness was significantly correlated with age, years since menopause, weight, and walking steps. There was no significant association between BsmI VDR genotypes and stiffness. The association between VDR genotypes and stiffness was analyzed in high and low walking steps groups (HW. LW) separated by the mean walking steps in each genotype and we found that VDR genotype had the most significant effect on stiffness (p< 0.01) as indicated by using two-factors (VDR genotypes × walking steps) mixed design analysis of covariance (ANCOVA) with the age, years since menopause and weight as covariates. A significant interaction of VDR genotype with walking steps was also observed (p 0.01) . Stiffness of HW was significantly higher than that of LW in both genotypes (Bb: p<0.01, bb: p<0.05) . Our findings showed that the correlation of walking steps with stiffness by simple regression analysis varied with VDR genotypes, but that the slope in Bb did not differ significantly from that in bb and this result did not change after adjustment for age, years since menopause and weight. From now on, further investigations will be needed to clarify the interaction between VDR genotypes and environmental factors in an effect on stiffness.