The purpose of this study is to elucidate effective tactics in judo matches for the visually impaired. This study investigates and analyses the score ratio and score acquisition rate of visually impaired judo athletes in competition. In visually impaired judo the rules of non-disabled judo are modified into four phases. The first phase starts immediately after the referee announces “kumi-kata” to just before the referee announces “hajime”. The second phase begins right after the referee announces “hajime” to just before the first throwing technique. The third phase is from the start of a throwing technique to the end of a throwing technique. The fourth phase is from the end of a throwing technique to the end of a katame-waza.
For this study data was compiled from 218 matches from domestic and international visually impaired judo championships. The tactical behavior of 1,375 nage-waza techniques were analyzed in sequence relating to kumi-kata combinations. The analysis was divided into the following categories: the controlled grip (CG); the presence or absence of the switch grip (SWG); the re-grip (RG); nage-waza; katame-waza, including the transition from a nage-waza; the penalties incurred during a match; and the match result. Statistical analysis of the data was performed using a chi-square test and a Fischer’s exact test with Microsoft Excel and R.
The results obtained show the ratio of kenka-yotsu score was significantly higher (χ2=5.837, df=1; p<0.05) than ai-yotsu in the CG. The score ratio was significantly higher (χ2=8.468, df=1; p<0.05) when SWG tactics were applied. The score ratio of the osaekomi-waza was significantly higher in the nage-waza with a score, and the score ratio of the shime-waza was significantly higher than the nage-waza without a score (χ2 = 9.416, df = 4, p <0.05).
The conclusions of this study indicate that in the overall match strategy where the first to second phases are performed with CG as kenka-yotsu, but without RG, it is tactically advantageous to use SWG only if your opponent avoids kenka-yotsu. In the fourth phase, however, it is clear that nage-waza while shifting to osaekomi-waza when a score is available, or shifting to osaekomi-waza or shime-waza when a score is not available, increases the rate of victory. It is hoped that the knowledge obtained from this study can be utilized not only to further develop the teaching methodology of both techniques and tactics for visually impaired judo athletes, but also to improve the overall competitiveness of judo.
