The Relative Age Effect and Performance in Rhythmic Gymnastics: An Analysis of the 2023 Junior and Senior World Championships

The relative age effect (RAE) refers to the advantage often observed in sports selection processes, where athletes born earlier in the calendar year are favored over those born later. While the RAE has been widely studied in various sports, little is known about its presence in rhythmic gymnastics (RG), a female-dominated esthetic sport characterized by early specialization. This study investigated the presence of the RAE among elite rhythmic gymnasts (RGs) at the international level, focusing on differences in birth quarter distribution across age categories and performance levels. The sample included 578 RGs—356 juniors and 222 seniors—competing in individual and group events. Birthdates were categorized into four quartiles (Q1–Q4). Chi-square goodness-of-fit tests and standardized residuals as post hoc tests were used to analyze the RAE. No significant RAE was found in the overall sample or when analyzed by geographic region (p > 0.05). However, a significant under-representation in Q4 occurred for Group RGs (SR = −2.17), and among all juniors (SR = −2.54) (χ2[3, 356] = 9.833, p < 0.05, w = 0.17), particularly in the subgroup of 15-year-old gymnasts, who were over-represented in Q3 (SR = 2.55; χ2[3, 183] = 10.027, p < 0.05, w = 0.23). Finalists—especially those in group events—also showed a higher proportion of Q3 athletes and a lower proportion of those born in Q4. Among junior finalists, Q4 was significantly under-represented (p < 0.05). These novel sport-specific findings suggest the presence of an atypical RAE pattern in RG, particularly in younger age groups and among high-performing athletes. RG coaches and policymakers should consider alternative selection models and adapt training approaches for Q4-born gymnasts in order to prevent early deselection.