Symmetry Analysis of Manual Wheelchair Propulsion Using Motion Capture Techniques

Abstract

There is no consensus among researchers on the biomechanics of wheelchair propulsion concerning the bilateral symmetry assumption. On one hand, the assumption is advantageous, as it allows for the simplification of data collection, processing, and analysis. It also facilitates the modelling of wheelchair propulsion biomechanics. On the other hand, there are reports that the validity of the bilateral symmetry assumption is unclear. Therefore, the present study aims to analyse the biomechanics of wheelchair propulsion for side-to-side differences. Motion capture techniques based on ArUco with the use of OpenCV libraries were used for this purpose. The research was carried out on a group of 10 healthy and inexperienced volunteers with a semi-circular propulsion pattern, who declared right-handedness. The tests were carried out on a hard, even surface, without an additional load, within the frequency of the propelling phases dictated by sound signals, amounting to 30 BPM. The positions of markers on the hand, elbow, and wrist were analysed. As a result, a cloud of points of the markers’ displacement on the sagittal plane in the propulsion push progress function was obtained. The results were averaged with a breakdown by the right and left hand for individual persons, but also for the entire group of volunteers. A comparative analysis and the mutual position of the confidence intervals of the determined mean values were also performed. The collected data suggest that the mean values for individual participants show greater asymmetry than the mean positions of the markers for the entire group of participants. Therefore, the assumption about the symmetry of upper limb propulsion may not be true when analysing the biomechanics of propulsion for individuals, although it may be accurate when analysing larger groups of persons (participants free of upper-extremity pain or impairment).