Evaluating the accuracy of the judging support system in artistic gymnastics compared to the 3D motion analysis system

This is the authors' abstract. We don't add key points for this paper.

In this study, the measurement accuracy of split angle data obtained using the Judging Support System (JSS), a markerless motion analysis system used in artistic gymnastics, was evaluated in comparison with a gold-standard optical motion capture system (VICON). Nine female collegiate artistic gymnasts executed split leap trials recorded simultaneously using both systems. We defined the split angle as the angle between the left and right leg vectors, each extending from the hip joint center to the toe center, and compared time-series waveforms and maximum split angles between systems. Agreement in maximum split angle was assessed using Bland–Altman analysis and the concordance correlation coefficient, and similarity in time-series movement patterns was evaluated using dynamic time warping. The JSS showed slightly larger maximum split angles than VICON, with a mean difference of − 1.1°, and no significant proportional bias was observed. Nevertheless, the concordance correlation coefficient was high across trials, and the time-series waveforms showed similar patterns during the aerial phase, including the maximum split angle. Temporal discrepancies were mainly observed during take-off and landing. These findings suggest that the JSS can capture the main time-series kinematic characteristics of split angle during split leap broadly comparable to those obtained using VICON, supporting its potential use as a practical biomechanical measurement tool in gymnastics.