Symmetry of the elbow kinematics during racing wheelchair propulsion

The purpose of this study was to establish whether bilateral symmetry exists during wheelchair propulsion in the elbow movement pattern of trained wheelchair racers. Seven endurance-trained wheelchair racers volunteered to participate in the study. Each subject was recorded by two-dimensional video analysis while pushing on a single-roller wheelchair ergometer at 14 mph (6.58 ms-1) in their own racing wheelchair. The range of elbow flexion, elbow orientation and selected timing parameters including cycle time and time spent in contact with the handrim (propulsion phase) were obtained from both left and right sides. Wilcoxon Matched-Pairs Signed-Ranks tests determined the differences between the left and right sagittal plane images of wheelchair propulsion. Furthermore, the Bland-Altman method determined the agreement between the left and right sagittal plane images. The results indicated that the propulsion phase, elbow height and elbow angular displacement characteristics were not significantly different between right and left sides. The right elbow was higher than the left during the recovery phase, but the magnitude of this difference was only 0.03 m (N.S). Factors associated with chair design and the athlete's posture may have contributed to the small differences noted between left and right sides. In conclusion, the results appear to suggest that the assumption of bilateral symmetry of the elbow movement pattern during wheelchair propulsion is valid for the group. However, it is important to note that asymmetries exist in individuals and further research is warranted.