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Mechanical efficiency of two commercial lever-propulsion mechanisms for manual wheelchair locomotion. Jordon Lui, BKin; Megan K. MacGillivray, MSc; A. William Sheel, PhD; Jeswin Jeyasurya, MASc; Mahsa Sadeghi, MD; Bonita Jean Sawatzky, PhD. Aim
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Mechanical efficiency of two commercial lever-propulsion mechanisms for manual wheelchair locomotion Jordon Lui, BKin; Megan K. MacGillivray, MSc; A. William Sheel, PhD; Jeswin Jeyasurya, MASc; Mahsa Sadeghi, MD; Bonita Jean Sawatzky, PhD
Aim • Evaluate mechanical efficiency (ME) of 2 lever-propulsion mechanisms (torsion spring and roller clutch) for wheelchairs. • Compare ME of lever vs hand rim propulsion within same wheelchair. • Relevance • Conventional wheelchairs have hand rims for manual propulsion, which can be energetically inefficient.
Method • Subjects • 10 nondisabled males. • Procedure • Performed submaximal exercise tests with both lever-propulsion mechanisms and hand rim propulsion on 2 different wheelchairs. • Measures • Cardiopulmonary parameters (O2 uptake [VO2], heart rate [HR], energy expenditure [En]). • Total external power (Pext) using drag test protocol. • ME (ratio of Pext to En).
Results • No significant effect by lever-propulsion mechanism for all physiological measures. • Suggests torsion spring didn’t have physiological benefit vs roller clutch mechanism. • Both lever-propulsion mechanisms showed decreased VO2 and HR and increased ME (as function of slope) vs hand rim propulsion.
Conclusion • Both lever-propulsion mechanisms tested are more mechanically efficient than conventional hand rim propulsion, especially when slopes are encountered.