Evaluation of selected indices of gait asymmetry for the assessment of running asymmetry

The methods of running asymmetry evaluation are not as highly developed as the methods of gait evaluation. Which asymmetry indices used in the gait analysis best characterize the asymmetry of the running movement? The kinematics of the sprint in a straight run over a distance of 50 m was evaluated using the X-sens system. Three indices (Ia, IS, SA) were based on discrete values from the first point of contact of the foot with the ground (1% of the running cycle phase) and were called discrete coefficients. Furthermore, two indices (SI, RAI) were used to evaluate asymmetry over the entire running cycle and were termed continuous coefficients. The study examined 21 elite and non-professional middle-distance runners of both sexes. The evaluation of the usefulness of individual indices for the evaluation of gait asymmetry was performed by means of the analysis of ROC curves and evaluation of data scatter on Bland-Altman charts. The values of discrete and continuous asymmetry coefficients were different to each other. In Bland-Altman plots there was a meaningful variety of discrete coefficients and a small variety of continuous coefficients. The analysis of ROC curves proves this assumption. Including the real curve course of angular placement in particular joints it is observed that continuous coefficients describe asymmetry of movement more precisely. It was found that the so-called continuous indices SI and RAI ensure the best identification of the phenomenon of movement asymmetry.