High-rate settlement and unconsciousness with shime-waza in young judo athletes from a video analytic study in Judo World Championships

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.Observational retrospective study.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.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 ± 3.5 s and 2.4 ± 2.0 s, respectively (p = 0.009); moreover, this duration was significantly correlated with the duration from unconsciousness to awareness (ρ = 0.480, p = 0.002). The cut-off point for symptom occurrence was a duration from unconsciousness to choking release of ≥4 s (area under the curve = 0.746, p = 0.003, odds ratio = 6.7).Considering the risk of unconsciousness and accompanying symptoms resulting from shime-waza, appropriate education and responses are required.