The Role of Biological Maturation and Relative Age in Player Selection During Transition Phases at a German Youth Football Academy

This study investigated the influence of biological maturation and relative age on player selection during transition phases in a German youth football academy. In addition, it examined the extent to which biological maturation and relative age were correlated among selected players. A total of 176 male football players (U12–U15), competing in their highest age-specific league, were assessed for maturity offset and relative age across four sessions per season (2020/21–2024/25). Progression to the subsequent age group was examined using penalized logistic regression models, while associations between maturity offset and relative age were evaluated using Spearman’s rank correlation coefficients. Regression analyses revealed no significant effects in the pooled sample; however, age-specific analyses identified significant maturity-related selection biases during the U14 → U15 (OR = 2.26, p = 0.026) and U15 → U16 (OR = 1.95, p = 0.042) transitions. Relative age was not a significant predictor of progression at any transition. Moderate negative associations between maturity offset and relative age were observed following the U12 (ρ = −0.47) and U13 (ρ = −0.37) transitions, whereas weaker associations were found following the U14 (ρ = −0.32) and U15 (ρ = −0.27) transitions. These findings indicate that progression decisions within the academy are influenced more strongly by maturity status than by relative age, particularly during the transition phases following the U14 and U15 seasons. Furthermore, the observed correlations indicate that maturity status and relative age are related, yet distinct, constructs whose association decreases with increasing age and therefore warrant separate consideration within talent pathways.