Relative-age effect on competition outcomes at the World Youth and World Junior Athletics Championships.

The relative-age effect refers to a higher frequency of athletes with birthdates earlier in the competitive year. Track and field athletics has a 2-year competitive cycle at youth and junior levels that could make it particularly susceptible to the effect. We have therefore investigated the effect in athletics event finalists (first to eighth place) at the 2008 Junior Championships (men and women aged ≤ 19 years; n=1479) and the 2009 Youth Championships (boys and girls aged 16-17 years; n=1445). Counts of finalists differing in age by 1 year were estimated with Poisson regression and compared as factor effects (with ×/÷ 90% confidence limits and assessment of magnitude). The factor effects were: junior men 2.1 (×/÷ 1.4, large); junior women 1.7 (×/÷ 1.4, moderate); youth boys 3.7 (×/÷ 1.4, very large); youth girls 2.1 (×/÷ 1.3, large). Analysis by event group indicated the age effect was greatest in youth boys' sprints & hurdles (4.0, ×/÷ 1.7, very large), throws (7.2, ×/÷ 2.3, very large) and jumps (5.6, ×/÷ 1.9, very large), whereas it was smallest in junior men's throws (1.4, ×/÷ 1.4, small) and youth girls' jumps (1.4, ×/÷ 1.4, small). In conclusion, the marked relative-age effects in athletics must exclude some talented younger athletes from youth and junior championships and presumably discourage them from continuing to senior championships. The consequences are a lower overall standard of performance and, for some athletes, termination of involvement in athletics before realising their full potential. An alternative structure and calendar is needed to make youth and junior athletics championships more equitable.