Relative importance of body composition, osteoporosis-related behaviors, and parental income on bone speed of sound in adolescent females.

INTRODUCTION

Adolescence provides a unique opportunity to employ strategies aimed at optimizing peak bone mass yet there are limited studies on the relationship between specific social constructs, osteoporosis-related behaviors, and bone health status in adolescent females. The purpose of this study was to examine associations between bone speed of sound (SOS) and body composition, osteoporosis-related health behaviors, and parental income in adolescent females.

METHODS

Four hundred forty-two female students in grades 9-12 from schools in Southern Ontario, Canada were measured for height, body mass, and percent body fat and completed a battery of instruments to assess osteoporosis-related health behaviors. Bone SOS was measured by transaxial quantitative ultrasound at the distal radius and midtibia.

RESULTS

Percent body fat was a negative correlate of tibial SOS. No significant correlation was found between physical activity and bone SOS yet physical activity was negatively related to adiposity. Hierarchical regression showed that age and percent body fat were the most important predictors of the variance in tibial SOS scores, with calcium intake having a weaker, yet significant, relationship. Age was the only statistically significant predictor of radial SOS. Users of oral contraceptives had higher radial SOS when controlling for age. Higher parental income was not associated with bone SOS but positive associations between parental income, daily calcium intake, and weekly physical activity were noted.

CONCLUSIONS

Bone SOS is reduced in adolescent females with increased adiposity, whereas it is positively influenced by oral contraceptives and daily calcium intake.