RELATION OF NUTRITION, BODY-COMPOSITION AND PHYSICAL-ACTIVITY TO SKELETAL DEVELOPMENT - A CROSS-SECTIONAL STUDY IN PREADOLESCENT FEMALES

Objective: To examine the relation of anthropometric and growth parame ters (weight, stature, body composition, age, and skeletal age), nutri tional factors, and physical activity to the total body and radius bon e mineral density and content and radiogrammetry parameters of the sec ond metacarpal. Study design: The study was a cross-sectional evaluati on of 456 healthy, Caucasian girls, ages 8 to 13 years, Multiple regre ssion models were created based on C-p statistics to determine the ass ociation between bone parameters and various independent variables. Re sults: Mean calcium intake was 956 +/- 381 mg/day, about 20% below the RDA of 1200 mg/day and about 36% below the threshold intake of approx imately 1500 mg/day. The most significant predictors for total body an d radius bone mineral density were corresponding bone areas, lean body mass, body fat, skeletal age, dietary calcium, and stature (only for total body) with corresponding R-2(adjusted) of 48% and 36%. The total body and radius bone mineral content was positively associated with c orresponding bone areas, lean body mass, body fat, calcium intake, and skeletal age with corresponding R-2(adjusted) of 86% and 72%. Energy expenditure (corrected for BMI) was stratified into quartiles and bone mass parameters were distributed accordingly. A statistically signifi cant difference in total body and radius bone mineral density and cont ent was noted between the fourth and lower quartiles (ANOVA, p < 0.05 to p < 0.0001). Conclusion: The most significant predictors of bone ma ss in preadolescent females evaluated in this study are bone area, lea n body mass, body fat, skeletal age and dietary calcium.