Unlocking fair play: battling age-related biases in identifying Chile's next athletic prodigies

Introduction: The relative age effect (RAE) refers to performance advantages for individuals born early in a selection period compared to later-born peers, potentially biasing early talent identification in youth sports. This study extends prior research on the Z Strategy for detecting sports talents in Chilean schoolchildren. Objective: To analyze the relative age effect in detecting potential sports talents among Chilean 8th-grade students using the 2013 Physical Education SIMCE database and Z Strategy results. Methodology: A retrospective cross-sectional study was conducted with a representative sample of approximately 12,000 8th-grade students (ages 13-16, 50% female) assessed in 2013. Anthropometric and physical fitness data were collected via standardized tests. The Z Strategy identified talents as students with values ≥2 standard deviations above the mean in at least one variable, standardized by age and sex. Birthdates were categorized into quartiles (Q1-Q4), and distributions were compared using chi-square tests. Results: 1,242 students (13%) were identified as potential talents. Males showed significant RAE with 36% born in Q1 versus 15% in Q4 (p<0.001), while females had uniform distribution (~25% per quartile). Overall, 61% of talents were born in the first half of the year compared to 38% in the second half. Discussion: Findings align with international literature indicating widespread RAE in youth sports, particularly stronger in males due to maturation differences, as reported in studies on soccer and athletics. The absence in females matches reports of weaker RAE in female contexts. Conclusions: RAE significantly biases talent detection in Chilean male students, necessitating adjustments for equitable identification.