Background: The aim of this study was to determine if a Relative Age Effect (RAE) is present in Polish National Football Teams. Material and methods: Birth date distributions of football players from youth Polish National Teams (Under 15 – Under 19) and the senior Polish National Team were compared. The sample (a total of 1801 players) included 909 youth players – U-15 (n=290), U-16 (n=221), U-17 (n=153), U-18 (n=157), and U-19 (n=88) – and 892 professional players who played in at least one official game for the senior Polish National Team. Results: ‪An over-representation of players born in the first quarter of each selection year was identified on all youth teams. Anova Friedman test confirmed that the number of players on youth National Teams is dependent on the month of birth. Anova Kruskala-Wallis test demonstrated a statistically significant difference in the number of players born in January, March, and May. The Relative Age Effect fades with increasing age, and vanishes in full, when players reach the senior Polish National Team level. Conclusions: ‪The bias in selection of youth players may lead to poor talent identification and discrimination in the recruitment of professional football players.



Author ORCID Identifier

Andrzej Szwarc https://orcid.org/0000-0003-4809-1178; Bartosz Dolanski https://orcid.org/0000-0002-1844-2160