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
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
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.