Examining the Birthdates Distribution of Beijing Olympic Athletes

Nuno Leite, Sara Santos, Bruno Gonçalves, Alexandra Silva, Ricardo Duarte, Jaime Sampaio


The aim of this study was to examine the birthdate distribution of the entire population of athletes who participated in the 2008 Olympic Games,considering independently and simultaneously the effect of the following factors: (i) gender, (ii) sport category, (iii) continent, and (iv)performance outcome.The sample included 10.900 athletes whose birthdates were gathered into quartiles and then inspected with chi-square test. The analyses performed to compare birthdates distribution considering each sport category (Individual, Combat, Net/Wall, Invasion/Team, Combined, Field/Run, Target and Early Specialization sports) separately by each continent and performance outcome.No differences were found in the birthdates distribution for gender (p > .05).However, the results revealed significant differences in Asian males of Combat sports (c2=12.2 p < .01), South American males of Invasion/Team sports (c2=9.7 p < .05), Asian females of target sports (c2=9.1 p < .05) and Asian females of Early specialization sports (c2=8.4 p < .05), with a tendency to be born earlier in the year calendar. However, the North American females of Invasion/Team sports (c2=13.9 p < .01) showed a trend to born more frequently in the middle of the year calendar. Our data were not entirely consistent with previous work, adding new insights to the relative age effects research. The influence of different levels of environmental constraints on athletes’ birthdate distribution is proposed as the theoretical explanation for the encountered findings.


Relative age; Talent development; Sports performance

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