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.
The purpose of this study was to understand the information processing ability of karatedo players from behavioral and physiological indices using a choice reaction test. Participants were seven men who belonged to a university karatedo club. The experiment was as follows. The participants carried out a choice reaction test for image stimulation by pressing a button with either hand. They were instructed to press a button with their right hand when an upper punch image was shown and with their left hand when a middle punch was shown. In addition, the image was partially occluded by a spatial occlusion paradigm. The three conditions for image occlusion were “no-occlusion condition”, “upper body occlusion condition”, and “lower body occlusion condition”. and were conducted in a random order. The reaction time from the presentation of the stimulus to the button press and the gazing area were measured as behavioral indices, and the latency and amplitude of P300 to the stimuli were measured as physiological indices. As a result, it was shown that the gazing area during task performance was mainly at the upper body. The reaction time also showed that the upper body occlusion condition was significantly delayed compared to the lower body occlusion condition, which implies that the information obtained from the upper limbs and the trunk is an important clue when judging the punching technique. Furthermore, since the P300 amplitude in the middle punch was significantly increased compared to the upper punch, it is speculated that the middle punch was judged with a higher degree of confidence. From the above, it is suggested that karatedo players perform reaction tasks with efficiently collected information inherent in the movements, especially for the middle punch, based on their past experience and knowledge.