Optimal Intensity and Duration of Walking Rehabilitation in Patients With Chronic Stroke

Abstract

ImportanceFor walking rehabilitation after stroke, training intensity and duration are critical dosing parameters that lack optimization.ObjectiveTo assess the optimal training intensity (vigorous vs moderate) and minimum training duration (4, 8, or 12 weeks) needed to maximize immediate improvement in walking capacity in patients with chronic stroke.Design, Setting, and ParticipantsThis multicenter randomized clinical trial using an intent-to-treat analysis was conducted from January 2019 to April 2022 at rehabilitation and exercise research laboratories. Survivors of a single stroke who were aged 40 to 80 years and had persistent walking limitations 6 months or more after the stroke were enrolled.InterventionsParticipants were randomized 1:1 to high-intensity interval training (HIIT) or moderate-intensity aerobic training (MAT), each involving 45 minutes of walking practice 3 times per week for 12 weeks. The HIIT protocol used repeated 30-second bursts of walking at maximum safe speed, alternated with 30- to 60-second rest periods, targeting a mean aerobic intensity above 60% of the heart rate reserve (HRR). The MAT protocol used continuous walking with speed adjusted to maintain an initial target of 40% of the HRR, progressing up to 60% of the HRR as tolerated.Main Outcomes and MeasuresThe main outcome was 6-minute walk test distance. Outcomes were assessed by blinded raters after 4, 8, and 12 weeks of training.ResultsOf 55 participants (mean [SD] age, 63 [10] years; 36 male [65.5%]), 27 were randomized to HIIT and 28 to MAT. The mean (SD) time since stroke was 2.5 (1.3) years, and mean (SD) 6-minute walk test distance at baseline was 239 (132) m. Participants attended 1675 of 1980 planned treatment visits (84.6%) and 197 of 220 planned testing visits (89.5%). No serious adverse events related to study procedures occurred. Groups had similar 6-minute walk test distance changes after 4 weeks (HIIT, 27 m [95% CI, 6-48 m]; MAT, 12 m [95% CI, −9 to 33 m]; mean difference, 15 m [95% CI, −13 to 42 m]; P = .28), but HIIT elicited greater gains after 8 weeks (58 m [95% CI, 39-76 m] vs 29 m [95% CI, 9-48 m]; mean difference, 29 m [95% CI, 5-54 m]; P = .02) and 12 weeks (71 m [95% CI, 49-94 m] vs 27 m [95% CI, 3-50 m]; mean difference, 44 m [95% CI, 14-74 m]; P = .005) of training; HIIT also showed greater improvements than MAT on some secondary measures of gait speed and fatigue.Conclusions and RelevanceThese findings show proof of concept that vigorous training intensity is a critical dosing parameter for walking rehabilitation. In patients with chronic stroke, vigorous walking exercise produced significant and meaningful gains in walking capacity with only 4 weeks of training, but at least 12 weeks were needed to maximize immediate gains.Trial RegistrationClinicalTrials.gov Identifier: NCT03760016

Effects of an Acute High Intensity Exercise Bout on Retention of Explicit, Strategic Locomotor Learning in Individuals With Chronic Stroke

“…25,26 These previous studies, and others, demonstrate that exercise regimens that achieve >70% of age-predicted maximal heart rate in people with chronic stroke are unable to elicit lactate changes >10 mmo l/L. 25,26,43,56,57 Nevertheless, the changes in lactate found with these high-intensity protocols in people post-stroke were associated with electroencephalographic changes and changes in circulating neurotrophic factors, indicating neuroplastic change. 25,26,43,56,57…”

Stepping Closer to Precision Rehabilitation

“…Altogether, Boyne et al present a well-designed and well-executed clinical trial that rigorously evaluates intensity and duration of task-specific walking practice after stroke. More rehabilitation trials like this in which clear hypotheses are matched with specific outcomes to evaluate prespecified hypotheses are needed.…”

“…It is with these features of gait practice and in this overall context that Boyne and colleagues conducted their clinical trial to define the optimal intensity and duration of walking rehabilitation in chronic stroke. The study investigators enrolled 55 patients aged 40 to 80 years with stroke 6 months to 5 years prior who had a walking speed 1 m/s or less but who were still able to walk at least 10 m over ground with assistive devices as needed.…”

“…The HIIT group also showed improved gait speed but no differences in aerobic capacity (VO 2 ) compared to MAT. The authors conclude that the mechanism by which HIIT may improve outcomes could be related to “neuromotor rather than cardiopulmonary adaptations.” Further defining what constitutes neuromotor adaptations for gait after stroke will be important for generalizing findings from this study.…”

“…The current trial, conducted over a decade later, further refines are understanding of features that can be targeted in gait training. The main experimental manipulation in this study was intensity.…”