Influence of varying level terrain on wheelchair propulsion biomechanics

Objective: To evaluate manual wheelchair propulsion across level ground conditions that are encountered during everyday life. Design: Subjects included 14 individuals (13 with spinal cord injury [SCI], 1 with spina bifida) who were experienced manual wheelchair users and had no current upper extremity injury or pain complaints. Subjects propelled their wheelchairs at a self-selected speed across four different level ground conditions, including smooth and aggregate concrete and tile and carpet flooring. Temporal and kinetic measurements were obtained bilaterally from instrumented wheelchair rims during the steady-state phase of propulsion. Results: There were no side-to-side differences for any of the temporal or kinetic variables. Propulsion velocity and pushrim contact time were consistent across ground conditions. Propulsion frequency was significantly greater during both concrete conditions than either tile or carpet ground conditions. Forces and moments were greatest during the aggregate concrete ground condition and lowest during propulsion across tile flooring. Conclusions: The rolling resistance of level surface terrain significantly impacts wheelchair propulsion biomechanics. Identification of environmental conditions that may contribute to upper extremity pathology is a step toward injury prevention and maintenance of functional abilities for the manual wheelchair user. These results may be used to assist with home and community terrain design to minimize the demands associated with wheelchair propulsion.