Variable-Ratio Pushrim-Activated Power-Assist Wheelchair Eases Wheeling over a Variety of Terrains for Elders

Objectives: To test (1) whether a prototype variable-ratio pushrim-activated power-assist wheelchair would decrease effort and perceived exertion associated with wheeling and (2) whether the prototype would be acceptable to elders. Design: Repeated-measures design. Setting: Biomechanics laboratory. Participants: Eleven elderly wheelers (mean age ± standard deviation, 70.7±7.8y). Interventions: Wheelers propelled their own wheelchairs and the prototype on a level surface, a carpet, and an incline. Main Outcome Measures: Surface electromyographic activity from upper limb and torso, heart rate, number of pushes, category-ratio scale of perceived exertion, and Consumer Assessment of Power Assist Wheelchairs. Results: Compared with subjects' own manual wheelchairs, the prototype was associated with lower heart rate elevation (P<.0125), lower perceived exertion (P<.0125), and reduced electromyographic activity in 5 of 8 muscles. Of the 11 participants, 10 found the prototype to be "very easy" or "easy" to push on level and inclined surfaces; 9 gave that assessment on carpeted and inclined surfaces. Seven would "definitely" or "probably" trade their manual chairs for the power-assist chair if given the opportunity. Nine thought they would venture to new and different places in a power-assist wheelchair. Time and number of pushes to complete tasks did not differ significantly between chairs. Conclusions: The prototype reduced the effort associated with wheeling and was an acceptable alternative to manual wheelchairs. Further testing outside the laboratory is warranted.