Relative age effect among U14 football players in Portugal: do geographical location, team quality and playing position matter?

Relative age effect (RAE) has been found to be particularly pronounced between 13 and 15 years of age in male football. However, the extent to which the phenomenon varies within a country demands a more comprehensive approach.To examine the effects ofA total of 2,693 players (mean age: 14.12 ± 0.38 years), selected by the 22 regional football associations for the last seven editions of the tournament (2013-2019), was included in the sample.Chi-square analysis showed a small-to-medium RAE in the U14 cohort compared to the general Portuguese male population (Our findings confirm that besides being present in U14 Portuguese male football, the magnitude of RAE is influenced by demographic factors. This study also supports the notion that coaching staffs tend to choose players based on attributes associated with chronological age, seeking to achieve short-term competitive outcomes.