Comparison of metabolic cost, performance, and efficiency of propulsion using an ergonomic hand drive mechanism and a conventional manual wheelchair

摘要

Objective To compare the metabolic cost (oxygen uptake per unit time [V?o2 consumption], heart rate, and number of pushes), performance (velocity and distance traveled), and efficiency (oxygen uptake per distance traveled [Vo2 efficiency]) of propulsion using a novel ergonomic hand drive mechanism (EHDM) and a conventional manual wheelchair (CMW). Design Repeated-measures crossover design. Setting Semicircular track. Participants Adult full-time manual wheelchair users with spinal cord injuries (N=12; mean age ± SD, 38.8±12.4y; mean body mass ± SD, 73.7±13.3kg; mean height ± SD, 173.6±11.1cm) who were medically and functionally stable and at least 6 months postinjury. Intervention Participants propelled themselves for 3.5 minutes at a self-selected pace in a CMW and in the same chair fitted with the EHDM. Main Outcome Measures Velocity, distance traveled, number of pushes, V?o2 consumption, Vo 2 efficiency, and heart rate were compared by wheelchair condition for the last 30 seconds of each trial using paired t tests (α=.01). Results The CMW condition resulted in more distance traveled (33.6±10.8m vs 22.4±7.8m; P=.001), greater velocity (1.12±0.4m/s vs.75±.30m/s; P=.001), and better Vo2 efficiency (.10±.03mL·kg-1·m-1 vs.15±.03mL·kg-1·m-1; P.001) than the EHDM condition, respectively. No significant differences were found between the 2 conditions for number of pushes (27.5±5.7 vs 25.7±5.4; P=.366), V?o2 consumption (6.43±1.9mL·kg -1·min-1 vs 6.19±1.7mL·kg -1·min-1; P=.573), or heart rate (100.5±14.5 beats per minute vs 97.4±20.2 beats per minute; P=.42). Conclusions The results demonstrate that metabolic costs did not differ significantly; however, performance and efficiency were sacrificed with the EHDM. Modifications to the EHDM (eg, addition of gearing) could rectify the performance and efficiency decrements while maintaining similar metabolic costs. Although not an ideal technology, the EHDM can be considered as an alternative mode of mobility by wheelchair users and rehabilitation specialists.