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 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.