Passive cycling in neurorehabilitation after spinal cord injury: A review

Context/Objective: Passive cycling (PC) may represent a potential alternative neurorehabilitation program for patients who are too weak or medically unstable to repeatedly practice active movements. We review here the most important animal and human studies addressing PC after spinal cord injury (SCI). Methods: A MEDLINE search was performed using following terms: "passive", "cycling", "pedaling", "pedalling","spinal cord injury". Results: Experimental studies revealed that PC modulated spinal reflex and reduced spasticity. PC also reduced autonomic dysreflexia and elicited cardio-protective effects. Increased levels of mRNA for brain-derived neurotrophic factor, glial cell line-derived neurotrophic factor and neurotrophin-4 were found. In contrast, human studies failed to show an effect of PC on spasticity reduction and did not support its application for prevention of cardiovascular disease-related secondary complications. Conclusion: Available evidence to support the use of PC as standard treatment in patients with SCI is still rather limited. Since it is conceivable that PC motion could elicit sensory inputs to activate cortical structures and induce cortical plasticity changes leading to improved lower limb motor performance, further carefully designed prospective studies in subjects with SCI are needed.