# Relative Age Effect in Olympic Karate: Evidence from Tokyo 2020

## TL;DR

This study finds that Olympic karate athletes born earlier in the year are more common, especially among females and in kumite, but birthdate doesn't affect medal success.

## Contribution

First evidence of relative age effect in Olympic karate, highlighting gender and discipline differences.

## Key findings

- More karate athletes were born in the first quartile compared to the last quartile.
- Relative age effect was stronger in kumite and among female athletes.
- Relative age did not predict Olympic medal success.

## Abstract

Background: The Relative Age Effect (RAE) refers to the advantage conferred to athletes born earlier within a selection year. In karate, particularly at the highest level, evidence is lacking. This study aimed to examine the presence of RAE among male and female karate athletes competing at the Tokyo 2020 Olympic Games, in two competitive disciplines: kata and kumite. Methods: Data from 81 athletes (42 males, 39 females) were retrieved from open-access databases. Birthdates were grouped into quartiles (Q1–Q4) and semesters (S1–S2). Chi-squared tests and odds ratios (ORs) were used to assess deviations from a uniform distribution, while binary logistic regression examined the association between semester of birth and medal attainment. Results: The overall distribution of birth quartiles significantly deviated from a uniform distribution (χ2(3) = 9.81, p = 0.020), indicating a higher proportion of athletes born in Q1 (38%) compared with Q4 (19%; OR = 2.07). RAE was particularly evident in kumite (χ2(3) = 17.87, p < 0.001; OR = 3.50 for Q1 vs. Q4) and among female athletes (χ2(3) = 9.92, p = 0.019), whereas no significant effect was found in kata or among males. Logistic regression revealed no significant association between semester of birth and medal success (OR = 0.49, 95% CI [0.20–1.21], p = 0.125). Conclusions: This study provides the first evidence of RAE in Olympic karate, especially among females and in kumite. However, relative age did not predict performance outcomes, suggesting that once athletes reach the Olympic level, technical and tactical factors outweigh birthdate advantages.