Exercise Intensity Matters in the Rehabilitation of Stroke in the Acute Stage: A Randomized Controlled Trial

Background: High-intensity interval training (HIIT) has emerged as a potentially effective exercise promoting functional recovery post-stroke. Objective: This study examined the efficacy of adding HIIT cycling vs. combining unloaded cycling (SHAM) to conventional physiotherapy on exercise capacity, functional ability, disability level, and health-related quality of life (HRQoL) early post-stroke. Methods: Forty-four acute stroke survivors were randomly assigned to the HIIT cycling or SHAM group for 6 weeks of exercise training, 3 days/week. The primary outcome was exercise capacity (peak work load [WRpeak]) measured by a maximal exercise test. Secondary outcomes included balance: Berg Balance Scale, walking ability: 6-minute and 10-meter walk tests (6MWT and 10mWT), lower-extremity muscle strength: 5-Repetition Sit-To-Stand test, disability level: modified Rankin Scale (mRS), and HRQoL by EuroQOL 5-dimension questionnaire. Results: The 2-way factorial analysis of variance showed a significant interaction of time × group on WRpeak ( P < .001), 6MWT ( P < .001), 10mWT ( P < .001), and mRS ( P = .012). The significant interaction indicates that the change in WRpeak (mean +17.7 W [95% CI, 10.2-25.1]), 6MWT (mean +126.8 m [77.9-175.7]), 10mWT (mean +0.5 m/s [0.3-0.7]), and mRS (mean −0.7 point [−1.2 to −0.2]) after 6-week of training was significantly greater for HIIT cycling versus SHAM. These changes are also significantly greater in the HIIT group vs the SHAM group up to 6 months ( P < .001) post-training. Conclusions: In individuals with acute stroke, individuals, combining HIIT cycling with conventional physiotherapy significantly maximizes recovery of exercise capacity and walking ability, and reduces the level of disability early post-stroke, compared to SHAM. Protocol Registration number: NCT06179173