Manual wheelchair propulsion on ramp slopes encountered when boarding public transit buses

Objective: To compare the kinetics of manual wheelchair (MWC) propulsion on ramps of that may be encountered when accessing large accessible transit vehicles (LATVs). Design: Observational study. Setting: Biomechanics research laboratory. Participants: A convenience sample of able-bodied adults (n = 7) having no propulsion experience propelled a MWC on ramps of slope 3.5 degrees, 9.5 degrees and 15 degrees. Interventions: Not applicable. Main outcome measures: Resultant (F-res), radial (F-r) and tangential (F-t) forces applied to the wheelchair pushrim, rate of rise of resultant force (ROR), peak power output (P), temporal characteristics and thigh to trunk angle were analyzed across three ramp slopes. Results: Pushrim forces and power output significantly increased with increasing slope, with peak F-res more than doubling from 107N on a 3.5 degrees slope to 230N on a 15 degrees slope. ROR was 1.76 times higher at 9.5 degrees and 2.47 times higher at 15 degrees compared to a 3.5 degrees slope. Minimum thigh to trunk angle decreased sharply from 80 degrees (3.5 degrees slope) to 50 degrees (9.5 degrees slope) and then to 30 degrees(15 degrees slope) as ramp slope increased. Conclusions: Ascending bus ramps require greater power and pushrim force on steeper ramp slopes, presenting a potential barrier to transportation accessibility. Given this finding, it is imperative that bus operators minimize ramp slope to assure MWC users are able to access LATVs.