Abstract
BackgroundStroke survivors experience chronic gait impairments, so rehabilitation has focused on restoring ambulatory capacity. High-intensity speed-based treadmill training (HISTT) is one form of walking rehabilitation that can improve walking, but its effectiveness has not been thoroughly investigated. Additionally, cortical priming with transcranial direct current stimulation (tDCS) and movement may enhance HISTT-induced improvements in walking, but there have been no systematic investigations. The objective of this study was to determine if motor priming can augment the effects of HISTT on walking in chronic stroke survivors.MethodsEighty-one chronic stroke survivors participated in a controlled trial with stratification into four groups: 1) control–15 min of rest (n = 20), 2) tDCS–15 min of stimulation-based priming with transcranial direct current stimulation (n = 21), 3) ankle motor tracking (AMT)–15 min of movement-based priming with targeted movements of the ankle and sham tDCS (n = 20), and 4) tDCS+AMT–15 min of concurrent tDCS and AMT (n = 20). Participants performed 12 sessions of HISTT (40 min/day, 3 days/week, 4 weeks). Primary outcome measure was walking speed. Secondary outcome measures included corticomotor excitability (CME). Outcomes were measured at pre, post, and 3-month follow-up assessments.ResultsHISTT improved walking speed for all groups, which was partially maintained 3 months after training. No significant difference in walking speed was seen between groups. The tDCS+AMT group demonstrated greater changes in CME than other groups. Individuals who demonstrated up-regulation of CME after tDCS increased walking speed more than down-regulators.ConclusionsOur results support the effectiveness of HISTT to improve walking; however, motor priming did not lead to additional improvements. Upregulation of CME in the tDCS+AMT group supports a potential role for priming in enhancing neural plasticity. Greater changes in walking were seen in tDCS up-regulators, suggesting that responsiveness to tDCS might play an important role in determining the capacity to respond to priming and HISTT.Trial registrationClinicalTrials.gov, NCT03492229. Registered 10 April 2018 – retrospectively registered, https://clinicaltrials.gov/ct2/show/NCT03492229.
Highlights
Stroke survivors experience chronic gait impairments, so rehabilitation has focused on restoring ambulatory capacity
Priming with transcranial direct current stimulation (tDCS), ankle motor tracking (AMT), or both did not enhance the effects of High-intensity speed-based treadmill training (HISTT) on walking speed, but tDCS+AMT enhanced ipsilesional corticomotor excitability (CME), which was retained at follow-up
The tDCS+AMT group had decreased motor threshold and increased recruitment curve slope in the ipsilesional hemisphere after training, both indicators of increased CME. These effects were retained 3 months after the end of training and are consistent with our finding that a single session of tDCS and HISTT increases CME [20]. These results suggest that motor priming paired with HISTT leads to long-term enhancement of CME
Summary
Stroke survivors experience chronic gait impairments, so rehabilitation has focused on restoring ambulatory capacity. High-intensity speed-based treadmill training (HISTT) is one form of walking rehabilitation that can improve walking, but its effectiveness has not been thoroughly investigated. The objective of this study was to determine if motor priming can augment the effects of HISTT on walking in chronic stroke survivors. Gait rehabilitation has focused on development of interventions to restore ambulatory capacity, and there is a critical need to maximize benefits of current walking training interventions. HISTT leads to greater improvements in overground walking speed than progressive treadmill training in chronic [11, 12] and sub-acute [13] stroke. The effectiveness of HISTT at improving clinical gait and neurophysiological outcomes post-stroke has not been thoroughly investigated
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