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Neural Plasticity
Volume 2016, Article ID 6718763, 13 pages
http://dx.doi.org/10.1155/2016/6718763
Research Article

Training-Specific Neural Plasticity in Spinal Reflexes after Incomplete Spinal Cord Injury

1Neuroscience and Mental Health Institute, University of Alberta, Edmonton, AB, Canada
2Faculty of Pharmacy & Pharmaceutical Sciences, University of Alberta, Edmonton, AB, Canada
3Department of Surgery, University of Alberta, Edmonton, AB, Canada
4Department of Biomedical Engineering, University of Alberta, Edmonton, AB, Canada
5Department of Physical Therapy, University of Alberta, Edmonton, AB, Canada

Received 29 March 2016; Revised 27 July 2016; Accepted 3 August 2016

Academic Editor: Malgorzata Kossut

Copyright © 2016 Atif S. Khan et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

The neural plasticity of spinal reflexes after two contrasting forms of walking training was determined in individuals with chronic, motor-incomplete spinal cord injury (SCI). Endurance Training involved treadmill walking for as long as possible, and Precision Training involved walking precisely over obstacles and onto targets overground. Twenty participants started either Endurance or Precision Training for 2 months and then crossed over after a 2-month rest period to the other form of training for 2 months. Measures were taken before and after each phase of training and rest. The cutaneomuscular reflex (CMR) during walking was evoked in the soleus (SOL) and tibialis anterior muscles by stimulating the posterior tibial nerve at the ankle. Clonus was estimated from the EMG power in the SOL during unperturbed walking. The inhibitory component of the SOL CMR was enhanced after Endurance but not Precision Training. Clonus did not change after either form of training. Participants with lower reflex excitability tended to be better walkers (i.e., faster walking speeds) prior to training, and the reduction in clonus was significantly correlated with the improvement in walking speed and distance. Thus, reflex excitability responded in a training-specific way, with the reduction in reflex excitability related to improvements in walking function. Trial registration number is NCT01765153.