Unmatched speed perceptions between overground and treadmill manual wheelchair propulsion in long-term manual wheelchair users

Background: Manual wheelchair (MWC) propulsion is increasingly assessed on a motorized treadmill (TM), which is often considered more ecologically valid than stationary rollers. However, no clear consensus on the similarities between overground (OG) and TM propulsion has yet been reached. Furthermore, no study has investigated the participants' perceptions of propelling a MWC on a TM compared to OG. Research question: The present study aims to assess the perception of speed when propelling on a TM vs OG, and to relate this perception to measured spatiotemporal variables, kinetics and work. Methods: In this repeated-measures study, the propulsion's spatiotemporal variables, kinetics, and work of nineteen experienced wheelchair users with a spinal cord injury were compared between three conditions: 1) OG at a self-selected speed, 2) on a TM at a self-selected speed perceived as being similar to the OG speed (TMperceived), and 3) on a TM at the same speed as OG (TMmatched). Each variable was compared between conditions using an analysis of variance for repeated measures. Results: All participants selected a lower speed for TMperceived than OG, with a difference of -0.6 m/s (-44%). This adaptation may be due to a combination of two factors: 1) the absence of speed information, and 2) the feeling of urgency to grab the wheels during the recovery phase. The power output, work per cycle, and work per minute were also much lower on TMperceived than OG. However, in contrast to other work on MWC propulsion on a TM, the kinetic variables assessed were all similar between the OG and TMmatched conditions. Significance: Training on a TM should be performed at a speed that matches the OG speed and not at a selfselected speed on the TM, which would reduce the power output and work and therefore reduce the efficiency of the training.