Affiliations: [a] Neural Rehabilitation Group, Cajal Institute, Consejo Superior de Investigaciones Científicas, Madrid, Spain
| [b] Sensorimotor Function Group, Hospital Nacional de Parapléjicos, Toledo, Spain
| [c]
Toledo Physiotherapy Research Group, Nursing and Physiotherapy School, Castilla La Mancha University, Toledo, Spain
| [d]
Health Sciences Institute, Consejería de Sanidad, Talavera de la Reina, Spain
| [e] Tecnológico de Monterrey, Mexico
| [f] Stoke Mandeville Spinal Research, National Spinal Injuries Centre, Aylesbury, UK
| [g] Harris Manchester College, University of Oxford, Oxford, UK
Correspondence:
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Address for correspondence: Stefano Piazza, Cajal Institute, Av Doctor Arce, 37, 28002 Madrid, Spain. Tel.: +34 915854750; Fax: +34 915854754; E-mail: stefano.piazza@csic.es.
Abstract: OBJECTIVE: Appropriate afferent feedback delivery during the execution of motor tasks is important for rehabilitation after incomplete spinal cord injury (iSCI). However, during leg-cycling therapy, the plantar afferent feedback is minimal. We hypothesize that the augmentation of sensory input by combining cycling with a locomotor-like stimulation of plantar cutaneous innervations (ES-cycling), might help to restore proper spinal processing of sensorimotor function. METHODS: Thirteen non-injured subjects and 10 subjects with iSCI performed 10 minutes of cycling and, on another session, of ES-cycling. To assess spinal processing of sensorimotor function, soleus H-reflex response was tested following a conditioning plantar electrical stimulation applied at 25–100 ms inter-stimulus intervals (ISI’s), measured before and after the execution of the tasks. RESULTS: Before tasks execution, the conditioned H-reflex response was modulated in non-injured subjects, and absent in subjects with iSCI; after cycling, modulation profiles were unchanged. However, after ES-cycling a significant increase in H-reflex excitability was observed in the non-injured group at 100 ms ISI (p < 0.05), and in the iSCI group between 50–75 ms ISI (p < 0.001). CONCLUSION: The loss of reflex modulation in subjects with iSCI suggests reduced spinal processing of sensorimotor function. Reflex modulation recovery after ES-cycling may indicate the partial reactivation of these mechanisms.
