Objectives: We aimed to investigate the incidence rate of unconsciousness related to shime-waza and the accompanying symptoms by age categories using video analysis of the Judo World Championships. Design: Observational retrospective study. Methods: We included 6918 elite judo athletes and 7426 bouts from the Judo World Championships between 2015 and 2021. Incidence rates of matches settled using shime-waza and unconsciousness were calculated by age categories: cadet, junior, and senior. Furthermore, in cases of unconsciousness resulting from shime-waza, the duration of choking initiation and release, unconsciousness, and awareness were recorded from video analysis and compared by the presence of post-awareness symptoms. A relationship between the duration of shime-waza and the post-awareness symptoms was investigated using receiver operating characteristic analysis. Results: Shime-waza was used to settle 307 (4.1%) bouts comprising 6.0%, 4.4%, and 3.0% of the cadet, junior, and senior bouts, respectively (p<0.001). The unconsciousness rates were 18.9%, 14.6%, and 4.3% in the cadet, junior (p=0.008), and senior bouts (p<0.001), respectively. Among the 39 unconsciousness cases, 24 (61.5%) showed convulsions or staggers after awareness. The duration from unconsciousness to choking release in cases with and without symptoms was 5.0±3.5s and 2.4±2.0s, respectively (p=0.009); moreover, this duration was significantly correlated with the duration from unconsciousness to awareness (p=0.480, p=0.002). The cut-off point for symptom occurrence was a duration from unconsciousness to choking release of =4s (area under the curve=0.746, p=0.003, odds ratio=6.7). Conclusions: Considering the risk of unconsciousness and accompanying symptoms resulting from shime-waza, appropriate education and responses are required.
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