Objective:

To estimate the effects of high-intensity interval training (HIIT) on balance, walking outcomes, and physiological endpoints after stroke, and to generate hypotheses about training-load parameters that may explain variability in intervention effects.

Approach:

• Search Strategy: Searched PubMed, Web of Science, Embase, Scopus, and the Cochrane Library for randomized controlled trials of HIIT in post-stroke populations.
• Data Extraction: Two reviewers independently screened records and extracted data, assessing risk of bias using RoB 2 and certainty of evidence using GRADE.
• Effect Size Calculation: Effect sizes calculated as Hedges' g using between-group change scores, with imputation for missing data.
• Statistical Analysis: Pooled estimates using three-level random-effects models; statistical inference based on cluster-robust variance estimation.
• Exploratory Analyses: Meta-regression and subgroup analyses conducted as hypothesis-generating analyses.

Key Findings:

• HIIT may improve balance (ES = 0.20, 95% CI 0.01 to 0.39, p = 0.039) with low certainty.
• HIIT may improve walking endurance (ES = 0.41, 95% CI 0.22 to 0.61, p < 0.001) with very low certainty.
• No significant effect on short-distance walking speed (ES = 0.06, 95% CI−0.16 to 0.29, p = 0.579).
• Possible improvement in cardiorespiratory fitness (ES = 0.36, 95% CI 0.05 to 0.66, p = 0.021) with very low certainty.
• No significant effects on blood pressure or stroke severity.

Interpretation:

Low- to very-low-certainty evidence suggests potential benefits of HIIT on balance, walking endurance, and cardiorespiratory fitness after stroke, while effects on other outcomes remain uncertain.

Limitations:

• Low to very low certainty of evidence across outcomes.
• Small number of trials and limited outcome-specific effect sizes.
• Exploratory findings should not be interpreted as evidence of optimal HIIT prescriptions.

Conclusion:

HIIT may have beneficial effects on certain post-stroke outcomes.

Sources:

• Systematic review registration