Use of power assist wheels results in increased distance traveled compared with conventional manual wheeling

Objective: To evaluate the impact of power assist wheels on the distance traveled by manual wheelchair users and analyze potential cofactors in the magnitude of response and to test the hypothesis that wheelers would travel significantly further with power assist wheels. Design: A 16-wk A (Preintervention)-B (Intervention)-A (Postintervention) repeated measures design. Seven women and 13 men (age, 43 ± 15 yrs) full-time wheelers participated. During the pre- and postintervention phases (4 wks each), participants used their own unaltered manual wheelchairs. During the 8-wk intervention phase, the manual wheels were replaced with power assist wheels. Daily distance was measured with bicycle-style odometers. A composite score of laboratory wheelchair tasks was used to classify wheelchair performance. Mixed model repeated measures analysis of variance analyzed changes across phases of the trial. A post hoc analysis tabulated the amount of days wheelers exceeded their individual daily averages in each phase by two SDs. Results: Wheelers traveled significantly greater distances during the intervention phase compared with pre- or postintervention phases regardless of baseline wheelchair performance. Wheelers who demonstrated higher baseline wheelchair performance traveled lesser average distances in the first 2 wks after receiving power assist wheels than in the subsequent 6 wks. Wheelers exceeded their individual daily averages per phase on a significantly greater number of days during the intervention phase. Conclusions: Power assist wheels enabled wheelers to travel farther and to travel beyond their usual distances on more days. Further studies may be strengthened by taking into account the 2-wk "adjustment phase" for power assist wheels.