ミニバスケットボール選手における相対的年齢効果についての検討：誕生月，試合出場時間，身長の関係性に着目して

<p>It is evident that differences in birth month affect various abilities and is known as relative age effect (RAE). This study aimed to clarify the RAE on the distribution of birth month, playing time, and height of mini basketball players and obtain suggestions for athlete development systems and coaching methods.</p><p>Players of a team participating in the 52nd All Japan Mini Basketball Games held in March 2021 were included in the study. We explained the purpose and content of the study to the team representatives verbally and in writing, and data were obtained from only players who provided parental consent. The number of collected questionnaires was 327, comprising 16 teams of 165 boys (42.1％) and 14 teams of 162 girls (35.9％). A total of 257 responses (126 boys and 131 girls) from the fifth and sixth grades of elementary school were analyzed.</p><p>The observations were as follows.</p><p>(1) There was a significant correlation between birth month and number of players registered on the bench, and the younger the relative age, the lower the number of registered players. However, there was no significant difference when compared to the expected frequency calculated from the percentage of births by month in Japan. (2) The existence of the RAE was suggested in the playing time of boys, and sex differences were revealed. (3) Among the boys, RAE was observed in terms of height. Additionally, there was a significant correlation between height and playing time. The results suggest that coaches should use more players with superior physique and higher relative age in games.</p>