In judo, an anterior cruciate ligament (ACL) injury is the most severe injury an athlete could experience. Most ACL ruptures occur when defending against an osoto-gari attack. This study aims to identify ACL risk factors during osoto-gari defence and implement a modified osoto-gari defence reaction, which is assumed to improve myoelectric patterns and ameliorate critical biomechanical risk factors for ACL injuries. Twenty-six elite judokas were enrolled in the cross-over trial (female: 6; male: 20). 3D kinematics and force dynamometrics were combined with electromyographical recordings to assess the effects of the common and the modified osoto-gari defence reaction. Compared to the common osoto-gari defence reaction (maximal knee flexion: 29 ± 12°; maximal valgus: 10 ± 5°; maximal valgus moment: 58 ± 17 Nm; peak internal rotation: 9 ± 5°), the modified osoto-gari defence reaction showed significantly reduced knee angles (31 ± 10° p < 0.05; 1 ± 0° p < 0.05; 31 ± 9 Nm p < 0.05; 3 ± 0° p < 0.05). The myoelectric activity of the hamstring increased (+5±% to +27±%, p < 0.05) in the modified compared to common defence reaction. The modified osoto-gari defence reaction reduced critical biomechanical risk factors and increased hamstring myoelectric activity. We recommend the implementation of the modified osoto-gari defence reaction in judo practice and seek to evaluate its long-term effectiveness in decreasing ACL injury incidences in elite judo.
Keywords: ACL; athlete; elite sports; kinematics; neuromuscular; reflex; sports medicine.