Manual wheelchair stroke characteristics during an extended period of propulsion

Study Design:Cross-sectional study.Objectives:The purpose of this study was to examine stroke characteristics of long-term manual wheelchair users during an extended manual wheelchair propulsion trial and the extent to which changes in propulsion biomechanics occurred.Setting:Human Engineering Research Laboratories, VA Rehabilitation Research and Development Center, VA Pittsburgh Healthcare Systems, Pittsburgh, PA, USA.Methods:Kinetic data were recorded from 21 subjects with paraplegia at four time points over the course of a 10-min propulsion trial at a steady state speed of 1.4 m s¹. Upper extremity kinetic parameters were recorded using Smartwheels, force and torque sensing pushrims.Results:Subjects for propulsion biomechanics changed from early to late during the 10-min trial. Individuals displayed decreased maximum rate of rise of resultant force (P0.0045) with a simultaneous increase in push time (P0.043) and stroke time (P 0.023), whereas stroke frequency remained static. In addition, there was a decrease in out of plane moment application (P 0.032).Conclusion:Individuals seemed to naturally accommodate their propulsive stroke, using less injurious propulsion biomechanics over the course of a 10-minute trial on a dynamometer. The findings may have occurred as a result of both biomechanical compensations to a challenging propulsion trial and accommodation to propelling on a dynamometer. These results suggest that subjects may be capable of independently incorporating favorable biomechanical strategies to meet the demands of a challenging propulsion scenario.