# High-Intensity Interval Training Enhances Cardiovascular and Functional Outcomes Compared With Moderate-Intensity Continuous Training in Higher-Functioning Chronic Stroke PMID: 41492722 Journal: Annals of rehabilitation medicine Published: 2025-12-01 Authors: Moon HM ## Question Does six weeks of supervised HIIT improve cardiovascular function, gait ability, and hematological variables more than exposure-matched MICT in higher-functioning chronic stroke survivors? ## Summary This single-blind randomized controlled trial compared HIIT with MICT in 29 higher-functioning ambulatory chronic stroke survivors. Both groups received 30 minutes of conventional physical therapy plus 40 minutes of aerobic training, three times weekly for six weeks. HIIT used six 1-minute bouts at 80%-100% HRmax separated by 4-minute active recovery at <=60% HRR, with warm-up and cool-down stretching, ECG monitoring, and therapist guidance. Compared with MICT, HIIT produced larger improvements in VO2max, HRmax, heart rate while walking, 10-meter walk, Timed Up and Go, and 6-minute walk distance. Lipid outcomes improved slightly within HIIT only, without between-group differences. No serious musculoskeletal adverse events occurred; two HIIT participants had transient mild muscle soreness. ## Population - Higher-functioning ambulatory chronic stroke survivors with stroke history longer than six months. - Sample size: 29 - Age: HIIT group 52.53 +/- 9.50 years; MICT group 50.00 +/- 8.75 years. - Sex: 16 male and 13 female total; HIIT 8 male/7 female, MICT 8 male/6 female. - Fitness level: Higher-functioning chronic stroke survivors; FAC >=4, BBS >=41, able to complete 6MWT. - Health status: Chronic stroke; participants with arrhythmia, uncontrolled hypertension, diabetes, COPD, congestive heart failure, unstable angina, peripheral arterial disease, orthopedic limitations, depression, or inability to undergo stress testing/high-intensity exercise were excluded. ## Methodology - Single-blind randomized controlled trial with two parallel groups. - Six weeks. - Inpatient and outpatient rehabilitation care settings; all protocolized sessions were supervised and completed in the same care setting for each participant. - Randomized and controlled study design. ## Protocol - HIIT. - Modality: Treadmill or cycle ergometer. - Work intervals: 1 minute at 80%-100% HRmax. - Recovery: 4 minutes active recovery at <=60% HRR. - Sets or repetitions: Six cycles. - Intensity: Prescribed HR-targeted intervals with continuous ECG monitoring. - Session duration: 70 minutes total, including 30 minutes conventional physical therapy and 40 minutes HIIT with 5-minute warm-up and 5-minute cool-down. - Frequency: Three sessions weekly. - Program length: Six weeks. - Progression: Resistance or workload adjusted to meet HR targets; no fixed progression schedule reported. - MICT. - Modality: Treadmill or cycle ergometer. - Work intervals: Continuous exercise. - Intensity: 60%-80% HRmax. - Session duration: 70 minutes total, including 30 minutes conventional physical therapy and 40 minutes MICT with 5-minute warm-up and 5-minute cool-down. - Frequency: Three sessions weekly. - Program length: Six weeks. - Progression: Therapists made real-time adjustments and verbal cueing to sustain target HR; no fixed progression schedule reported. ## Outcomes ### VO2max Status: improved HIIT improved VO2max substantially more than MICT. HIIT 19.70 +/- 1.24 to 22.77 +/- 1.84, change +3.07 +/- 0.60; MICT 19.65 +/- 0.71 to 19.98 +/- 0.99, change +0.33 +/- 0.28; F=40.574, p=0.001, partial eta2=0.603. ### HRmax Status: improved HIIT increased HRmax more than MICT. HIIT change +4.14 +/- 0.66 bpm; MICT change +0.68 +/- 0.73 bpm; F=24.661, p=0.001, partial eta2=0.484. ### Heart rate while walking Status: improved HIIT reduced heart rate while walking more than MICT, suggesting improved submaximal efficiency. HIIT change -2.94 +/- 0.41 bpm; MICT change -0.85 +/- 0.11 bpm; F=11.277, p=0.002, partial eta2=0.308. ### 10-Meter Walk Test Status: improved Both groups improved, with greater improvement after HIIT. HIIT change -1.83 +/- 0.01 s; MICT change -1.04 +/- 0.17 s; F=20.865, p=0.001, partial eta2=0.517. ### Timed Up and Go Status: improved Both groups improved, with greater improvement after HIIT. HIIT change -1.59 +/- 0.08 s; MICT change -0.96 +/- 3.27 s; F=12.317, p=0.002, partial eta2=0.430. ### 6-Minute Walk Test Status: improved HIIT improved walking endurance more than MICT; only HIIT showed significant within-group improvement. HIIT change +8.67 +/- 1.83 m; MICT change +2.35 +/- 1.41 m; F=9.742, p=0.004, partial eta2=0.325. ### Blood lipids Status: mixed LDL, HDL, and TG showed small significant within-HIIT improvements but no significant group-time interactions. LDL F=0.682, p=0.418; HDL F=0.453, p=0.507; TG F=0.813, p=0.371. ### Safety Status: no clear change No serious musculoskeletal adverse events occurred; two HIIT participants had transient mild muscle soreness that resolved without stopping training. ## Practical Insights - A supervised 1-minute hard, 4-minute active recovery protocol can improve VO2max and walking outcomes in screened higher-functioning chronic stroke survivors. - Longer recovery intervals may be appropriate for clinical populations where recovery capacity and safety matter. - Heart-rate guided delivery and monitoring were central to protocol fidelity; consumer translation should be conservative and screening-dependent. - MICT may need longer duration or higher frequency to produce comparable cardiorespiratory adaptations in this population. ## Limitations - Small sample size. - Six-week intervention with no long-term follow-up. - Limited to higher-functioning ambulatory chronic stroke survivors. - Inpatient and outpatient settings varied, and some outpatients received additional therapy outside the trial. - Unmeasured co-interventions cannot be fully excluded. - Time-to-target and exposure metrics were post hoc descriptive analyses. - Mechanical workload was not standardized across treadmill and cycle modalities. ## Safety And Adherence - No serious musculoskeletal adverse events were observed. - Two HIIT participants reported transient mild muscle soreness that resolved spontaneously without interruption of training. - Continuous ECG monitoring and therapist guidance were used during training. - The authors caution that HIIT may pose risks in patients with significant cardiovascular comorbidities or severely impaired physical function. ## Original Sources - [PubMed](https://pubmed.ncbi.nlm.nih.gov/41492722/) (pubmed) - [DOI](https://doi.org/10.5535/arm.250098) (doi) - [PMC full text](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC12869853/) (full text) ## Agent Guidance Preserve the paper-level scope of this note. Do not generalize beyond the population, protocol, measured outcomes, and limitations above.