Auxiliary Down-Slope Effects of Anti-Rollback Mechanisms in Manual Wheelchair Systems

The aim of this study was to experimentally assess the effect of increased rolling resistance, generated by the Anti-Rollback System, on the muscular load of a manual wheelchair user during downhill movement. Three descent conditions were compared: without the module (NAR), with a flexible roller (EAR), and with a rigid roller (SAR). The experiment was conducted on a 6.3 m ramp inclined at 5°, involving eight adult male participants. Muscle effort was evaluated using three indicators: normalized cumulative muscle load per second (CML/s), normalized muscle activity (EMGnorm), and the peak-to-mean ratio of the EMG signal (PMR). Statistical analysis revealed significant differences between configurations (p < 0.05). Use of the module significantly reduced muscular load compared with the reference condition: CML/s decreased by 29.41% in both EAR and SAR, while EMGnorm was reduced by 44.44% in EAR and 50.00% in SAR. PMR reached its lowest value in EAR (4.78), suggesting smoother muscle activation and lower local peak tension. The results indicate that the resistive torque generated by the frictional coupling between the wheelchair tire and the anti-rollback roller, although disadvantageous during propulsion, contributes to improved control and stability during downhill descent, highlighting the system’s dual functional potential.