Injury Characteristics Among Japanese International Athletes: Report on the Pre-competition Medical Check-Up Data of the Japanese Olympic Committee.

Introduction Injury trends among international athletes across sports remain underexplored in out-of-competition settings, particularly among Asians. The aim of this descriptive epidemiological study is to investigate the characteristics of injuries among Japanese international athletes during pre-competition medical check-ups from 2008 to 2019. Methods We analyzed the medical check-up data of candidates for international multi-sport events according to the International Olympic Committee consensus statement. At the medical check-up, athletes' injuries were categorized into two groups based on clinical assessment. "Injuries" refer to conditions that necessitate immediate treatment or further detailed examination. On the other hand, "complaints" encompass both such "injuries" and conditions for which treatment has already commenced, allowing athletes to continue participating in competitions or training while still requiring ongoing medical monitoring. The cohort was categorized into youth and adult groups, with adults defined as those aged ≥18 years. Results Overall, 10,854 athletes (4,966 females, 45.8%; 5,888 males, 54.2%; median age 22.0 {20.0-25.0} years, 56 sports) were enrolled; 2,333 "injuries" were registered (21.5 "injuries" per 100 athletes). The "injury" prevalence was 16.2% (95% CI, 0.16-0.17) and significantly associated with females (odds ratio {OR} 1.21; 95% CI, 1.09-1.34) and adult group (OR, 1.35; 95% CI, 1.08-1.69) based on binomial logistic regression analysis. Of a total of 10,027 "complaints" (92.4 "complaints" per 100 athletes), the "complaint" prevalence was 55.3% (95% CI, 0.54-0.56) and higher in females (OR, 1.44; 95% CI, 1.33-1.55) and adult group (OR, 1.50; 95% CI, 1.29-1.75). Stratified by sport, male soccer players had a higher "injury" prevalence than females (95% CI, 0.45-0.98), whereas females had a higher "injury" prevalence in hockey (1.70-7.29) and fencing (1.12-5.44). The "complaint" prevalence was higher in females for athletics, skiing, swimming, hockey, judo, badminton, fencing, water polo, weightlifting, and golf. There was no significant difference between the sexes in other sports. The knee ("injury," 20.1%; "complaint," 20.2%), lumbosacral (15.5%; 17.0%), ankle (13.0%; 15.4%), and shoulder (13.0%; 12.1%) were most commonly affected. The injury proportion ratio for the ankle was "injury"/"complaint" 0.82 (95% CI, 0.72-0.94), with the ankle "complaint" proportion being higher than "injury." When stratified by injury location and sex, knee "injury" was more common in males (206 in females vs. 262 in males; 95% CI, 0.59-0.88), whereas ankle "complaint" was more common in females (842 in females vs. 700 in males; 95% CI, 1.04-1.29). Conclusion This is the first cross-sectional report of injuries in Asian international athletes outside of competition periods. Injury prevalence was higher in females than in males and in adults than in youths. Sex differences in injury varied by site and severity. These findings may suggest the need for more tailored injury prevention and performance support strategies for international competitions.