PMID 41492722

Research
All papers

High-Intensity Interval Training Enhances Cardiovascular and Functional Outcomes Compared With Moderate-Intensity Continuous Training in Higher-Functioning Chronic Stroke

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.

Methodology

  • Higher-functioning ambulatory chronic stroke survivors with stroke history longer than six months.
  • 29 participants.
  • Treadmill or cycle ergometer.
  • Work intervals: 1 minute at 80%-100% HRmax.
  • Recovery: 4 minutes active recovery at <=60% HRR.
  • Intensity: Prescribed HR-targeted intervals with continuous ECG monitoring.
  • 70 minutes total, including 30 minutes conventional physical therapy and 40 minutes HIIT with 5-minute warm-up and 5-minute cool-down.
  • Three sessions weekly.
  • Six weeks.
  • Single-blind randomized controlled trial with two parallel groups.
  • VO2max, Maximum heart rate, Heart rate while walking, and 10-Meter Walk Test were tracked.

Outcomes

VO2max

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.

Improved

HRmax

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.

Improved

Heart rate while walking

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.

Improved

10-Meter Walk Test

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.

Improved

Timed Up and Go

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.

Improved

6-Minute Walk Test

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.

Improved

Blood lipids

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.

Mixed

Safety

No serious musculoskeletal adverse events occurred; two HIIT participants had transient mild muscle soreness that resolved without stopping training.

No clear change

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

  • 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.