PMID 41891032

Research
All papers

Submaximal Exercise Testing to Dose High-Intensity Interval Training After Stroke: The FAST Randomized Clinical Trial

Bartsch BL, Engler A, Schneider N, Britton-Carpenter AJ, Baldridge T, Montgomery RN, Vidoni ED, Moores A, Vetter ES, Hazen EM, Abraham M, Billinger SA

Question

In adults with chronic stroke, does HIIT dosed from a total-body recumbent-stepper submaximal exercise test improve predicted VO2peak, vascular measures, and walking outcomes more than moderate-intensity continuous training?

Summary

In 49 adults with chronic stroke, 4 weeks of supervised recumbent-stepper HIIT prescribed from a submaximal exercise test was compared with moderate continuous training. Both groups trained 3 times weekly, attended nearly all sessions, achieved target intensity, improved predicted VO2peak and walking outcomes, and had no study-related serious adverse events. HIIT did not outperform MICT for the primary fitness outcome over 4 weeks, but HIIT showed within-group improvement in peripheral flow-mediated dilation.

Methodology

  • Community-dwelling adults with chronic ischemic or hemorrhagic stroke at least 6 months prior to enrollment.
  • 49 participants.
  • Total-body recumbent stepper.
  • Work intervals: 1 minute at 65%-95% PPO and 90-100 spm.
  • Recovery: 1 minute active recovery at 10% PPO and about 50 spm.
  • Intensity: Vigorous-intensity intervals prescribed from PPO derived from a TBRS submaximal exercise test.
  • 25-minute main set plus standardized warm-up and cool-down.
  • 3 sessions/week.
  • 4 weeks.
  • Single-site randomized parallel-group preliminary efficacy trial comparing HIIT with MICT.
  • Predicted VO2peak, Flow-mediated dilation, Resting middle cerebral artery velocity, and Gait speed were tracked.

Outcomes

Predicted VO2peak

Both groups improved from baseline, but HIIT was not superior to MICT.

Between-group beta=-0.58, SE 0.93, p=0.54; HIIT +1.13 mL/kg/min (95% CI 0.05 to 2.21), p=0.04; MICT +1.58 (95% CI 0.18 to 2.97), p=0.03.

Improved

Peripheral vascular function

No significant between-group effect, but HIIT improved flow-mediated dilation within group in both stroke-affected and non-affected arms.

Stroke-affected arm beta=0.48, SE 1.09, p=0.66; non-affected arm beta=0.42, SE 0.85, p=0.62. HIIT within-group changes: +1.43%, p=0.02 and +1.60%, p=0.04.

Mixed

Walking outcomes

No significant between-group differences; both groups improved fast gait speed and walking endurance, and MICT improved comfortable gait speed.

Comfortable gait speed beta=-0.06, SE 0.04, p=0.19; fast gait speed beta=0.03, SE 0.04, p=0.53; 6-minute walk beta=9.04, SE 10.32, p=0.39.

Improved

Treatment fidelity and adherence

Attendance was near complete and HIIT achieved vigorous-intensity heart rates during most prescribed intervals.

Attendance 99.5% overall; HIIT achieved vigorous HR during 80.6% of prescribed high-intensity intervals; HIIT lactate higher than MICT by 0.735 mmol/L (95% CI 0.353 to 1.117), p<0.001.

Improved

Safety

Adverse events occurred, but no serious adverse events were study-related.

24 AEs among 17 participants; 6 possibly/definitely intervention-related; 1 hospitalization SAE unrelated.

Mixed

Insights

  • In supervised chronic-stroke rehabilitation, a 1-minute on/1-minute active recovery HIIT format can be delivered with high adherence when prescribed from submaximal testing and monitored.
  • Early 4-week improvements in fitness and walking may depend on adequate aerobic dosing rather than interval format alone.
  • HIIT superiority claims should be avoided for short-term predicted VO2peak based on this trial.
  • Clinical HIIT safety evidence depends on screening, individualized dosing, continuous monitoring, and clinician oversight.

Limitations

  • Modest sample size.
  • Preliminary efficacy design not powered for definitive comparison.
  • Single-site study.
  • Short 4-week intervention.
  • Predicted rather than directly measured VO2peak primary outcome.
  • No objective monitoring of outside physical activity.
  • No long-term maintenance assessment.
  • Chronic stroke population only.

Safety

  • No study-related serious adverse events occurred.
  • 17 participants had 24 adverse events: 10 in HIIT and 14 in MICT.
  • Six AEs were possibly or definitely related to the intervention.
  • Study-related AEs led to one dose reduction and three temporary pauses.