On the road to Cybathlon 2024: lessons learned from the Polimi FES-bike team

Background: Cybathlon competition is designed to promote innovation and usability of assistive technologies. Among its disciplines there is the Functional Electrical Stimulation (FES) bike race for people with Spinal Cord Injury (SCI). The aim of the race in 2024 was to cover 1960 m under 8 min. This work sums up the experience of the Polimi team on the road to Cybathlon 2024. Methods: A commercial recumbent trike was instrumented to enable FES-cycling. Moreover, a motor was added to the setup. While this motor was not mounted during the competition, it was used to optimize the stimulation angular ranges based on measurements of tangential forces and during the training sessions. Two subjects with complete SCI were recruited as pilots of our team. One of them completed the entire training protocol, which was based on the periodization principle to organize the training regimen in terms of training volume and intensity. Results and discussion: The stimulation ranges, which were experimentally optimised on the pilot who participated in the Cybathlon, resulted in a 99% increase in the time required for the cadence-based proportional-integral (PI) controller, used to modulate the stimulation currents, to reach saturation. The designed training regimen was successfully implemented and contributed to our pilot’s qualification for the final, where he achieved third place. Conclusion: The proposed solution demonstrated its efficacy within the context of the FES-bike race. Events such as Cybathlon highlight the potential of FES-cycling and underscore the importance of promoting its widespread adoption beyond clinical settings, including among people with SCI and other user populations.