Cardio-respiratory and subjective strains sustained by paraplegic subjects, when travelling on a cross slope in a manual wheelchair (MWC)

The aim of this study was to quantify cardiac, energetic and subjective strains during manual wheelchair (MWC) travel on cross slopes (Cs). 25 paraplegics achieved eight 300 m propulsion tests combining 4 Cs (0, 2, 8 and 12%) and 2 velocities (Vi = 0.97 m s−1, Vc “comfortable”). Heart rate and oxygen uptake were recorded continuously. Subjective rating (RPE) was made on completion of each test. Vc exceeds Vi for all Cs. Cardiac and energetic strains at Vc also exceed those at Vi (p < 0.01). Mean cardiac cost (in bpm) at Vc is 34 (SD = 13) bpm for a 0/2% Cs and 55 (18) bpm for a 12% Cs. Mean energetic cost (in J m−1 kg−1) is 1.20 (0.38) and 2.76 (0.97) for respectively 0/2% and 12% Cs at Vi and, at Vc 1.50 (0.43) and 3.37 (1.43) for 0/2% and 12% Cs respectively. Subjective rating was considered as moderate for a 12% Cs. MWC users with high level injuries travel faster as those with low level injuries. Strain increase is linear for Cs from 0% to 12%. The results suggest that 2% Cs is generally acceptable, while 8% would be a critical threshold.