The relative age effect in Brazilian soccer: so what?

Abstract

Objectiveː our purpose was a) to describe the Relative Age Effect occurrence in Brazilian elite youth soccer players; b) to identify the association between Relative Age Effect and technical skills and c) to examine how Relative Age Effect can affect Physical Fitness.
 Method: Eighty-one Brazilian elite soccer players from three age-group teams (U-15, U-17 and U-20) were classified by birth quartiles according to their date of birth. Relative Age Effect was determined when there was a statistically significant difference between players who were born in BQ1 (January through March) to the other birth quartiles (Chi-Square). The association between Relative Age Effect and Technical Rankings was verified by the correlation. The partial correlation controlled for date of birth and for maturity offset was also performed. Relative Age Effect on Physical Fitness was verified by the variance (ANOVA) of its components on each team’s birth quartiles.
 Results: Players born in BQ1 were the most selected in U-15 (60%) and U-17 (35%) teams, but not in U-20 (25%). A low to moderate (Rho = 0.04 to 0.53) correlation was found between birth quartiles and Technical Rankings, while date of birth and maturation (partial correlation) effects were identified in the U-15 team. Although birth quartiles do not affect Physical Fitness (ANOVA), it may favour some Physical Fitness components (p < 0.05).
 Conclusions: The greater risk of Relative Age Effect in younger teams is due to the greater emphasis on technical skills. When date of birth and maturation are controlled for, the association between Technical Rankings and birth quartiles is reduced. There was no evidence that Relative Age Effect affected the players’ game performance.