Variable-ratio pushrim-activated power-assist wheelchair eases wheeling over a variety of terrains for elders

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.

Repeated-measures design.

Biomechanics laboratory.

Eleven elderly wheelers (mean age +/- standard deviation, 70.7+/-7.8 y).

Wheelers propelled their own wheelchairs and the prototype on a level surface, a carpet, and an incline.

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.

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.

The prototype reduced the effort associated with wheeling and was an acceptable alternative to manual wheelchairs. Further testing outside the laboratory is warranted.