Modified defense reaction reduces biomechanical and myoelectrical ACL injury risk factors in elite Judo

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 degrees; maximal valgus: 10 +/- 5 degrees; maximal valgus moment: 58 +/- 17 Nm; peak internal rotation: 9 +/- 5 degrees), the modified osoto-gari defence reaction showed significantly reduced knee angles (31 +/- 10 degrees p < 0.05; 1 +/- 0 degrees p < 0.05; 31 +/- 9 Nm p < 0.05; 3 +/- 0 degrees 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.