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Improved efficiency with a wheelchair propelled by the legs using voluntary activity or electric stimulation
R B Stein1, S L Chong, K B James
1Division of Neuroscience, University of Alberta, Edmonton, Alberta, Canada. Richard.Stein@Ualberta.ca
Objective:
To determine whether a new leg-propelled wheelchair provides enhanced efficiency and mobility to wheelchair users.
Design:
Observational; subjects were tested while wheeling with the arms and legs and while walking (where possible) for 4-minute periods in random order with approximately 10-minute rest periods between exercise sets.
Setting:
Tests were done on an indoor 200-meter track.
Patients:
Group 1, 13 controls; group 2, 9 persons with complete spinal cord injury (SCI); group 3, 13 persons with other motor disorders (retaining some voluntary control of the legs).
Interventions:
Not applicable.
Main Outcome Measures:
Physiological Cost Index (PCI), (computed as change in heart rate divided by velocity of movement) and oxygen consumption (VO(2))
Results:
Arm wheeling took significantly more effort (mean PCI =.52 beats/m) than walking (.33 beats/m) in control subjects. Leg wheeling was most efficient (.23), requiring less than half the effort of arm wheeling and 30% less effort than walking. For SCI subjects, leg wheeling with functional electric stimulation (FES) required less than half the effort (.18) of arm wheeling (.40). The FES group could not walk. Subjects in group 3 could walk, but with substantial effort (1.81) compared with arm (.76) or leg wheeling (.64). Results for VO(2) were similar.
Conclusions:
Better wheelchair efficiency can be obtained for many disabled individuals, by moving the leg muscles voluntarily or with FES.