Efficiency and perceived exertion of manual wheelchair propulsion: a physiological comparison of push vs pull wheeling.

Manual wheelchair users face a high prevalence of upper extremity pain and injuries associated with poor biomechanics and the relatively low mechanical efficiency of conventional push wheeling. Recently developed geared wheels, which permit the wheelchair user to propel forwards by pulling at the handrims using a 'rowing' motion, have been speculated to improve ergonomics and reduce operational energy costs. This study compared the gross mechanical efficiency (GME) and perceived exertion (RPE) of these geared wheels to standard wheelchair wheels after a motor skill-based training session was conducted to familiarise participants with using both wheels. Fourteen able-bodied males were enrolled in the study. A within-participants, repeated-measures design was used to assess oxygen uptake (VO2), respiratory exchange ratio (RER), energy expenditure (En) and RPE during 5-minute, steady-state wheeling trials. Total external power output (Pext) was obtained using a drag test protocol for comparison over En to determine GME ratio. Stroke frequency and movement pattern were assessed through video tracking and propulsion testing. Although geared wheels required fewer strokes, standard wheels resulted in significantly lower VO2, RPE and En (p ≤ 0.001). These findings suggest overall that standard wheels were more mechanically efficient, likely due to internal energy loss of the geared wheel system.