2012 年 10 巻 p. 30-38
In the present study, we aimed to determine whether the advancement in skeletal age (SA) of youth soccer players relative to chronological age was dependent on the maturation spurt or selection bias toward biological maturation. These factors were investigated using cross-sectional and mixed longitudinal study designs. Height, body mass, SA, and maturation differences in 181 youth soccer players (age range; 9.3-16.0 years) were measured. SAs were assessed using the Tanner-Whitehouse three (TW3) and Japanese-standardized SA (J-SA) methods. Thirty-seven of the 181 players (age range; 9.6-13.0 years) then participated in a one-year follow-up study. The participants were divided into seven age groups (under 10 (U10)-U16). Cross-sectional differences in all measurements between the categories were compared with annual increment data. There were significant cross-sectional differences in height (14.9 vs. 10.9±3.3 cm), body mass (13.4 vs. 8.2±3.1 kg), and SA (J-SA: 1.7 vs. 1.0±0.6 yrs; TW3: 2.6 vs. 1.5±0.8 years) between the U12 and U13 groups (p<0.01 each). Furthermore, these differences were higher than those for mixed longitudinal data. These findings imply that advanced biological maturation in youth soccer players may depend on selection bias towards the early biological maturation.