Kinematic Variability of Wheelchair Propulsion: The Effects of Speed and Exercise

The population of manual wheelchair users is increasing notably faster than the general population. Manual wheelchair users have a disproportionately high prevalence of shoulder pain and injury, most likely due to the repetitive and load-bearing nature of propulsion. Previous wheelchair propulsion studies have reported on the kinematics of propulsion using traditional time-series data (e.g., propulsion cycle time, shoulder range of motion, et cetera) in an attempt to predict individuals at risk for developing shoulder pathology. However, a reliable method of prediction has yet to be attained using these metrics. Due to the repetitive nature of wheelchair propulsion cycle-to-cycle variability (i.e., inter-cycle variability) of the traditional kinematic indices may provide additional insight into the movement patterns of the shoulder during wheelchair propulsion. The purposes of these studies were to quantify baseline kinematic variability of the shoulder during manual wheelchair propulsion, quantify the effects of multiple speeds on shoulder kinematic variability, and quantify the effects of an exercise intervention on shoulder kinematic variability. There is some evidence that temporal and spatial kinematic variability may provide additional insight into wheelchair propulsion biomechanics beyond that of traditional measures of kinematics. However, when extrapolating the results of these studies to studies previously reported, discrepancies arise and are very likely due to methodological differences. These issues are discussed and a protocol was developed to help contribute to the standardization of biomechanical testing for wheelchair propulsion.