O Efeito De Idade Relativa No Futebol Em Portugal: O Caso Das Seleções Nacionais Femininas

Abstract

This study aimed to analyze the Relative Age Effect in Portuguese women's football, focusing on players from the national teams. The investigation was justified by the growing relevance of the sport both nationally and internationally, as well as by the need to understand how relative age may influence athletic development pathways and competitive participation. The sample consisted of the historical records of players from different competitive levels (U15, U16, U17, U18, U19, U23, B, and Senior National Team), obtained from open-access online databases of the Portuguese Football Federation. The Relative Age Effect was assessed through the distribution of birth dates by quartiles, using chi-square tests and Odds Ratios (95% CI), complemented by analyses stratified by playing position and game time. Binomial and Poisson regression models were implemented to assess the relationship between birth quartiles and minutes played, while a longitudinal analysis examined player re-selection across age categories. The results showed that the Relative Age Effect was most evident in younger age groups, favoring players born in the first quartile of the year, decreasing in intermediate categories, and reversing in senior contexts. Additionally, greater vulnerability was observed among goalkeepers, defenders, and midfielders, while forwards displayed the opposite trend. Conversely, birth quartile had no significant influence on playing time, with competitive level being the most determining factor. In summary, the findings confirm that the Relative Age Effect functions as an initial selection filter but diminishes with age, as technical, tactical, and psychological factors gain prominence in athletic performance. These results align with international literature, although some national particularities justify continuous monitoring. From a practical perspective, the study highlights the importance of implementing mitigating measures in talent identification and selection processes, aiming to promote greater equity and contribute to the sustainable development of women's football in Portugal.