Short-term changes in spinal cord excitability after backward walking with and without body weight support

Abstract

Walking is a simple and cost-effective tool for rehabilitation. It decreases spinal cord reflex excitability and might be useful for minimizing symptoms associated with spasticity, which is common in certain diseases such as multiple sclerosis. Particularly, walking in relatively challenging condition presents stronger effects than a typical forward walking. Additionally, body weight support during gait might be suitable for patients with impaired locomotion. However, there is no available data of short-term spinal cord neuroplasticity after backward walking (BW) with or without weight relief. The present study showed a significant reduction in H-reflex amplitude (the electrical analog of the stretch reflex) after 20 min of BW over a treadmill, with or without 20% of body weight support (p<0.05). It was also detected a significant shift of the recruitment curve (RC) to the right in both conditions, indicating that increased stimulus intensity is needed for reflex activation (p<0.05). No significant difference was detected in both H-reflex amplitude and stimulus intensities after 45 min from the ending of the walking task. The short-term after-effects were not associated with presynaptic inhibition of Ia terminals, suggesting that the presynaptic mechanism acting on Ia afferent terminals might not mediate the reduction in reflex excitability.