Cardiorespiratory Fitness Benefits of High-Intensity Interval Training After Stroke: A Randomized Controlled Trial.

Background: Limited evidence supports the effects of short-interval high-intensity interval training (HIIT) for improving cardiorespiratory fitness (V̇O ₂ peak) after stroke. We aimed to compare the effects of 12 weeks of short-interval HIIT versus moderate-intensity continuous training (MICT) on V̇O ₂ peak, cardiovascular risk factors, and mobility outcomes among individuals ≥6 months poststroke.
Methods: This study was a multi-site, 12-week randomized controlled trial (NCT03614585) with an 8-week follow-up. Participants were randomized into 3 d/wk of HIIT (10×1 minute 80%-100% heart rate reserve interspersed with 1 minute 30% heart rate reserve [19 minutes]) or MICT (20-30 minutes 40%-60% heart rate reserve). Secondary outcomes of the trial, including V̇O ₂ peak, cardiovascular risk factors (carotid-femoral pulse wave velocity, blood pressure, and waist-hip ratio), and mobility (6-minute walk test, 10 m gait speed), were reported. Linear mixed model analyses with a group×study time point interaction evaluated between-group differences.
Results: Of the 305 potential participants, 82 consented (mean [SD] age 64.9 [9.3] years, 32 females [39%], 1.8 [1.2] years poststroke) and were randomized to HIIT (n=42, mean [SD] baseline V̇O ₂ peak 17.3 [5.9] mL/kg·min) or MICT (n=40, mean [SD] baseline V̇O ₂ peak 17.2 [6.0] mL/kg·min). Participants attended 82% of visits (n=2417/2952). No adverse events occurred during the study period. A significant group×study time point interaction was found (χ ² =8.46; P =0.015) for V̇O ₂ peak at 12 weeks (mean difference, 1.81 [95% CI, 0.58-3.04]; P =0.004) whereby the HIIT group had greater gains in V̇O ₂ peak (∆3.52 mL/kg·min [95% CI, 2.47-4.57]; P <0.001) compared with the MICT group (∆1.71 mL/kg·min [95% CI, 0.55-2.86]; P =0.001). There was no between-group difference in V̇O ₂ peak (mean difference, 1.08 [95% CI, -0.26 to 2.42]; P =0.11) at 8-week follow-up. No group×study time point interactions were found for cardiovascular risk factors or mobility outcomes.
Conclusions: Short-interval HIIT may be an effective alternative to MICT for improving V̇O ₂ peak at 12 weeks postintervention.
Registration: URL: https://clinicaltrials.gov; Unique identifier: NCT03614585.
Competing Interests: Dr Moncion and K.S. Noguchi are supported by an Ontario Graduate Scholarship. L. Rodrigues is supported by a Doctoral Scholarship from the Fonds Recherche Santé Québec. Dr Eng is supported by the Canada Research Chairs program. Dr Roig is supported by a Salary Award (Junior II) from Fonds de Recherche Santé Québec. This study is funded by an operating grant from the Canadian Institutes of Health Research (388320). Dr Tang reports grants from Canadian Institutes of Health Research; grants from Physiotherapy Foundation of Canada; and grants from Heart and Stroke Foundation of Canada.