Abstract
BACKGROUND: The Relative Age Effect (RAE) refers to the advantage in physical and psychological development that children born earlier in the year often experience, which can influence their participation in sports. AIM: Analyze the influence of RAE on motor competence (MC) in school-aged children, focusing on differences across birth quartiles and types of sports participation. METHODS: A cross-sectional study was conducted with 1,031 children aged 12.02 ± 2.95 years, stratified by birth quartile (Q1-Q4) and sports participation. MC was assessed using the Motor Competence Assessment (MCA) test battery. Statistical analyses included one-way ANOVA and a three-way MANCOVA. RESULTS: Participants born in Q1 exhibited significantly higher MC scores compared to those born in Q3 and Q4, particularly in the Manipulative domain (p < 0.05, η (2) = 0.01). Sports participation had the strongest effect (p < 0.01, η (2) = 0.10), with participants in team sports demonstrating higher MC across all domains. Boys outperformed girls in Manipulative skills (p < 0.01, η (2) = 0.12). Furthermore, the interaction between birth quartile, sports participation, and sex was also significant (p = 0.02, η (2) = 0.01), indicating that the influence of RAE on MC depends on additional contextual factors. CONCLUSIONS: While RAE had a statistically significant but small effect on MC, sports participation, particularly team sports, and sex may play more dominant roles. These findings underscore the importance of promoting equitable access to organized physical activity while considering the nuanced and context-dependent nature of the RAE.