Long-Term Plasticity in Reflex Excitability Induced by Five Weeks of Arm and Leg Cycling Training after Stroke.

Taryn Klarner,E Zehr,Trevor Barss,Pamela Loadman,Yao Sun,Chelsea Kaupp

doi:10.3390/brainsci6040054

Taryn Klarner, E Zehr + Show 4 more

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https://doi.org/10.3390/brainsci6040054

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Abstract

Neural connections remain partially viable after stroke, and access to these residual connections provides a substrate for training-induced plasticity. The objective of this project was to test if reflex excitability could be modified with arm and leg (A & L) cycling training. Nineteen individuals with chronic stroke (more than six months postlesion) performed 30 min of A & L cycling training three times a week for five weeks. Changes in reflex excitability were inferred from modulation of cutaneous and stretch reflexes. A multiple baseline (three pretests) within-subject control design was used. Plasticity in reflex excitability was determined as an increase in the conditioning effect of arm cycling on soleus stretch reflex amplitude on the more affected side, by the index of modulation, and by the modulation ratio between sides for cutaneous reflexes. In general, A & L cycling training induces plasticity and modifies reflex excitability after stroke.

Highlights

The arms and the legs are coupled in the human nervous system such that activity in the arms affects activity in the legs and vice versa
The modulation index for the more affected (MA) flexor carpi radialis (FCR) and the modulation index ratio for the SOL and tibialis anterior (TA) have a post-test value that fell outside of the 95% confidence interval (CI) band from the pre-test sessions
For bEMG, the modulation index for the MA TA, MA FCR and less affected (LA) posterior deltoid (PD), and modulation index ratio for the TA, the average post-test value fell outside of the 95% CI from the pretest sessions

Summary

Introduction

The arms and the legs are coupled in the human nervous system such that activity in the arms affects activity in the legs and vice versa. Repeated-measures ANOVA was used to assess the effects of A & L cycling training with significance set at p ≤ 0.05. This representation is useful for showing the general trends in the evoked responses independent of the phase of the step cycle [60,68] Such grand averages taken irrespective of phase only provide an “at a glance” qualitative assessment of changes, and provide a visual representation of the strongest effects. Features such as phase-dependent reflex reversals, which occur only in a few phases, are obscured by this process and, may appear as “noise”. Standard error) reflex amplitude averaged across participants baselineand andpost-test post-test values

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