The Effect of Chronological Age (Birth Month) and Bone Age on Physique and Physical Performance of Children Involved in Athletic Gifted Children Selection Program

Abstract

PURPOSE:The importance of chronological age (CA, birth month) and bone age (BA) in explaining variation in physique, and also CA, BA and physique to variability in physical fitness (PF) were investigated in a sample of 513 elementary school children 2nd-6th grade. METHODS:The data collection period lasted 7 years (1,085 cases from 2009 to 2015). BA was assessed according to the Tanner-Whitehouse III technique. Physique included weight (BW), height (HT), chest girth (CG), BMI, and percentage of body fat (%fat), while physical performance tests included measure of muscle endurance, power, speed, agility, cardiovascular endurance and flexibility. Grade-specific stepwise multiple regressions were used to investigate both the relative importance of BA and CA in explaining physique and the relative importance of BA, CA and physique in explaining physical performance. RESULTS:BA is the best predictor of BW (R 2 =.110-.852), HT (R 2 =.120-.445), BMI (R 2 =.047-.232), %fat (R 2 =.034-.053) in this order. CA per se is the only partially significant predictor of physique. However, CA, %fat, CA, CG, HT, BW, BA, BMI were the significant predictors of physical performance, explaining between 6% and 65% of the variance in this study. Especially, CA and %fat were the primary predictors of physical performance except flexibility in both boys and girls of 2nd-6th grade.CONCLUSIONS: It showed that the strongest predictor of physique was BA, while CA and %fat were the best predictors of physical performance with the exception of flexibility in children involved in elementary athletic gifted children selection program.