Relative age effects and implications for sport performance in elite Chinese junior male basketball players

The relative age effects (RAE) have been a hot topic in the field of sport research, and although the phenomenon has been found in most sports in China, there is currently no literature on the RAE phenomenon in Chinese basketball, which has implications for explaining some of the phenomena in that sport. A large body of research suggests that RAE contributes significantly to the phenomena of brain drain and inequality in sport participation. The purpose of this study was to analyze whether RAE exists in Chinese youth men's basketball and whether RAE has an impact on the performance of athletes and teams, thus supporting the subsequent proposal of measures to balance the age effect.

This study analyzed the date of birth and performance rankings of all male athletes (n = 3926) who participated in the Chinese Youth Basketball Championships (U14, U15, and U17) from 2021 to 2023. The study divided the month of birth into quarters and semesters. Differences between actual observed and theoretical birth date distributions were statistically analyzed using the chi-square test, and subsequent calculations were made using the dominance ratio test.

It was found that RAE was present in all three groups of Chinese youth male basketball players (p < 001). The percentages of athletes born in the first half of the year were 61.2% (U14), 59.9% (U15), and 59.0% (U17), and the percentages of athletes born in the first quarter were 38.6% (U14), 35.8% (U15), and 34.8% (U17).

As a result of RAE, U15 athletes born closer to the beginning of the year are likely to achieve better results, whereas athletes born closer to the end of the year are less likely to achieve athletic excellence.