Quantification of motor abilities during the execution of judo techniques

PURPOSE: Quantitative performance analysis is of great importance, especially to increase personalized training and to reduce injuries. The use of inertial sensors has given many possibilities and has been largely used in analysing technical capabilities of athletes. With respect to combat sports, judo has many issues due to the great number of variables involved in the techniques and due to the critical measurement environment. The aim of this study was to propose a method for measuring and quantifying motor abilities objectively.  METHODS: Four inertial sensors were fixed to the lower limbs and one on the sternum of five male and five female elite judo athletes. Accelerations and angular velocities of the lower limbs were measured in 480 judo techniques. Regression lines of accelerations and angular velocities have been analysed to obtain 5 single technique indexes and 1 overall technique index representing the motor abilities connected, respectively, to the force expressions and the coordination capabilities.  RESULTS: Correlations of motor abilities (force expression and coordination capabilities) and athletes’ weight and height were found in only 6.7% of pairs. Results of force expression and coordination capabilities for most of the athletes are in line with their level of technical and combat experience.  CONCLUSIONS: This method allowed to "photograph" athlete's technical level and to compare it in time through subsequent trials. With this innovative way, motor abilities could become evaluable and measurable, highlighting the importance of their objective quantification in order to evaluate effectiveness and efficiency of the sport technique.