DETERMINANTS OF AXIAL AND PERIPHERAL BONE MASS IN CHINESE ADOLESCENTS

Objective-To determine the relation of puberty, physical activity, phy sical fitness, and calcium intake with bone mineral content (BMC) of t he distal radius, and on bone mineral density (BMD) of the L2 to L4 ve rtebrae in a group of healthy Chinese adolescents. Design-Cross sectio nal survey. Subjects-A group of 179 healthy Chinese adolescents (92 bo ys and 87 girls) aged 12 to 13 years enrolled in the first year of the Tii Junior High School in Shatin, Hong Kong. Ninety four of the pupil s enrolled were in the physical education major class (PE), and the ot her 85 were in the art major class (ARTS). Main outcome measures-Corre lation of BMC of the distal radius and BMD of the L2 to L4 vertebrae w ith level of physical activity, physical fitness (isometric and isokin etic), muscle strength of the upper and lower limb, and calcium intake . Results-BMC of the distal radius and BMD of the L2 to L4 vertebrae w ere significantly positively correlated. Univariate and regression ana lysis showed that age, pubertal staging, physical fitness, and muscle strength were significantly associated with bone mass in a positive wa y. Calcium intake and type of Sport practised did nor exert a signific ant influence on EMC of the distal radius and BMD of the L2 to L3 vert ebrae in boys. The results for the BMD of the L2 to L3 vertebrae were similar in girls and boys; however, in girls, the BMC of the distal ra dius had a negative correlation with calcium intake. Physical fitness was a significant positive predictor of BMD of the L2 to L4 vertebrae. Conclusions-Among Chinese adolescents bone mass was positively influe nced by certain measures of physical fitness as well as by age, weight , and pubertal stage.