The effect of high-intensity interval training on cardiorespiratory fitness for non-ambulatory stroke survivors: a randomized controlled trial.

PURPOSE: To compare the effects of high-intensity interval training (HIIT) in improving cardiorespiratory fitness (CRF) with low-intensity continuous training (LICT) in non-ambulatory stroke patients. METHODS: 40 non-ambulatory patients (33 men) with ischemic or hemorrhagic stroke (mean age 53 years) were randomly allocated to the intervention (n = 20) or control group (n = 20). Participants in the intervention group underwent HIIT (1 min high-intensity alternated with 1 min low-intensity), and those in the control group underwent LICT. The training protocol was repeated five times per week for four consecutive weeks (20 training sessions). The patients were assessed before and after the intervention. The primary outcome measure was peak oxygen uptake (VO2peak). The secondary outcomes were VO2AT, modified Rankin Scale(mRS), Barthel index (BI), and Fugl-Meyer assessment lower limb (FMA-LL). RESULTS: No differences were found between the two groups at baseline for clinical messages or functional levels (P > 0.05). BI, and FMA-LL all increased following training in both the HIIT and LICT groups. There was no statistically significant difference in pre-to-post changes in VO2peak across the HIIT and LICT groups (P = 0.665). However, Subgroup analysis revealed that among patients with admission BI ≥60, the HIIT group exhibited significantly higher post-intervention VO2peak than the LICT group (16.35 ± 3.53 vs. 12.74 ± 2.60 mL·kg-1·min-1, P = 0.020). Additionally, post-intervention VO2peak in the HIIT group was significantly higher in the normal-weight subgroup (BMI ≤24) than in the overweight subgroup (16.90 ± 3.11 vs. 13.51 ± 2.02 mL·kg-1·min-1, P = 0.016). CONCLUSIONS: Overall, a 4-week short-interval HIIT program was not superior to LICT in improving cardiorespiratory fitness among non-ambulatory stroke patients. Exploratory subgroup analyses suggested that HIIT may confer greater benefit in patients with higher admission activity levels (Barthel Index ≥60) and normal BMI (≤24 kg/m2). Future trials with longer durations and larger sample sizes are needed to confirm its precise efficacy and to develop more effective aerobic exercise protocols for non-ambulatory patients. CLINICAL TRIAL REGISTRATION: Chinese Clinical Trial Registry, ChiCTR2000035352.