Determining the impact of in-bed leg cycling on spinal cord excitability during the acute phase following spinal cord injury

Abstract Study Design : Prospective exploratory interventional study. Objective : This study evaluates the impact of in-bed leg cycling on spinal cord excitability during the acute phase following acute traumatic spinal cord injury (SCI). Setting : Level 1 trauma center specialized in SCI care in Montreal, Canada. Methods : Eighteen participants with traumatic SCI underwent a single 30-minute session of in-bed leg cycling during acute hospitalization, with motor assistance as needed. Using soleus H-reflex testing, H-reflex and M-wave responses were recorded pre- and post-session to assess the change in spinal cord excitability. Results : Changes in H-reflex parameters were observed after cycling even when performed passively. There were three main phenotypes but also large variability with regard to spinal cord excitability in response to cycling. Most individuals (9/18) had decreased excitability after cycling, while 6/18 individuals had increased excitability. A third group (3/18) did not exhibit any significant response to cycling. Spinal cord excitability never increased after cycling when performed 2 weeks or more after the SCI. Conclusions : Performing in-bed leg cycling during the acute phase following traumatic SCI appears to modulate spinal cord excitability, but responses are highly individualized.