Effects of High-Intensity Interval Training After Stroke (The HIIT Stroke Study) on Physical and Cognitive Function: A Multicenter Randomized Controlled Trial

ObjectiveTo assess the effects of high-intensity interval training (HIIT) on physical, mental, and cognitive functioning after stroke.DesignThe HIIT Stroke Study was a single-blind, multicenter, parallel-group randomized controlled trial.SettingSpecialized rehabilitation units at 3 Norwegian hospitals.ParticipantsAdult stroke survivors (N=70) 3 months to 5 years after a first-ever stroke. Mean age was 57.6±9.2 years and 58.7±9.2 years in the intervention and control groups, respectively.InterventionsParticipants were randomized to standard care in combination with 4×4 minutes of treadmill HIIT at 85%-95% of peak heart rate or standard care only.OutcomesOutcomes were measured using physical, mental, and cognitive tests and the FIM and Stroke Impact Scale. Linear mixed models were used to analyze differences between groups at posttest and 12-month follow-up.ResultsThe intervention group showed a significant treatment effect (95% confidence interval [CI]) from baseline to posttest on a 6-minute walk test of 28.3 (CI, 2.80-53.77) meters (P=.030); Berg Balance Scale 1.27 (CI, 0.17-2.28) points (P=.025); and Trail Making Test Part B (TMT-B; −24.16 [CI, −46.35 to −1.98] s, P=.033). The intervention group showed significantly greater improvement on TMT-B at the 12-month follow-up (25.44 [CI, −49.01 to −1.87] s, P=.035). The control group showed significantly greater improvement in total Functional Independence Measure score with a treatment effect of −2.37 (CI, −4.30 to −0.44) points (P=.016) at 12-month follow-up. No significant differences were identified between groups on other outcomes at any time point.ConclusionsHIIT combined with standard care improved walking distance, balance, and executive function immediately after the intervention compared with standard care only. However, only TMT-B remained significant at the 12-month follow-up.