Lifestyle factors affecting heel ultrasound in Greek females across different life stages

Abstract

The use of quantitative ultrasound (QUS) of the bone is rapidly gaining in popularity, and QUS is widely used worldwide for the assessment of skeletal status. Although much has been learned about the influence of various factors on ultrasonic parameters in various populations, similar information at the local level is not available. This study was carried out to examine the effects of anthropometric, dietary, physical activity, reproductive, and other lifestyle factors on QUS parameters in healthy Greek women, including children (n=217), adults (n=235), and elderly (n=369) subjects. Calcaneal QUS measurements were performed with the SAHARA device, which measures broadband ultrasound attenuation (BUA) and speed of sound (SOS) through the os calcis; a composite parameter, the quantitative ultrasound index (QUI), and an estimate of heel bone mineral density (eBMD) were also derived. All QUS indices were higher in adult women than in girls or elderly women (P<0.05). The latter had a similar BUA to girls, but lower SOS, QUI, and eBMD (P<0.05). Most QUS parameters correlated positively with height, weight, body mass index (BMI), hip circumference, organized physical activity, and activity promoting bone mass, but negatively with the time devoted to sedentary activities and absolute carbohydrate intake (P<0.05). Age of menarche and years since menopause were negatively associated with QUS in the adult and elderly women, respectively (P<0.05). The latter relationship, however, was due to the confounding effect of advancing age. Overweight and obese females had significantly higher BUA and eBMD than normal-weight subjects (P<0.05), but similar SOS and QUI; this held true for all age groups. Likewise, in all ages, individuals spending more than 2 h/week on organized activities had significantly higher QUS indices than those spending less time on exercise (P<0.05). Further, postmenarchial girls had significantly higher age-adjusted BUA, SOS, QUI, and eBMD than premenarchial ones (P<0.05). Similarly, all QUS parameters were significantly higher in adult women with an early onset of menarche (<14 years old) than in those with a late onset (P<0.05), but no effects of menarche were detected among the elderly. No significant effects of calcium intake (which was generally adequate), smoking or alcohol drinking (which were generally low) on QUS indices were observed, in either age group. Available independent variables could explain approximately 16%-24% of the total variance in BUA, SOS, QUI and eBMD. The most important positive predictors of QUS were adulthood, time devoted to organized activities, and weight or BMI, while age and carbohydrate intake per se contributed negatively. In conclusion, age, body size, physical activity, and some aspects of reproductive history and diet appear to variably affect calcaneal QUS indices among otherwise healthy Greek women at different life stages.