Modeling of grasps in judo contests

In judo, the two contestants get close to each other, perform their grasps, move on the mat and attack. The approaches and kumi-kata (grip technique) give way to specific behaviors between the two contestants. The briefness and the capacity of simultaneous actions, the multiple interactions and the result at stake result in a complex system that is most of the time clarified by the coach to the contestant. A computerized observation may help to highlight some actions associated to success from that complex system. The winners of 35 contests were analyzed (9 beginners, 16 intermediate levels, and 10 experts) through their behaviors (approaches and kumi-kata) and positions. The results enable experts to assume lengths (15.8±9.5s) and amount (9±6) of the combat phases (lapse of time between beginning and stop, announced by the referee) similar to the other two groups. Beginners approach each other with much care and precision, mainly holding their opponents with both hands for the projection. The percentage of total time spent by beginners and experts grabbing the opponent’s judogi with both hands, attack and throw was 86% and 24%, respectively, indicating a much lower time spent between grip contact and technique application in experts compared to beginners.