Higher Heart Rates During Locomotor High-Intensity Interval Training Are Associated With Gait Asymmetry and Fatigue After Stroke.
Alicen A Whitaker-Hilbig, Pierce Boyne, Darcy S Reisman and 4 others
More asymmetric step length and less fatigue at baseline predicted higher heart rate in the first week of HIIT for 27 people with chronic stroke.
No baseline walking measure predicted intensity across 12 weeks. Intensity rose by session 6.
Key findings
1Less baseline step length symmetry (more asymmetry) was associated with a higher average heart rate reserve during the first week of HIIT. This association remained after controlling for peak heart rate, respiratory exchange ratio, and self-reported fatigue.
2Lower baseline self-reported fatigue was associated with a higher average heart rate reserve during the first week of HIIT.
3No baseline walking characteristic (endurance, comfortable or fast speed, step length symmetry, single-limb support symmetry, metabolic cost) was associated with heart rate reserve across the full 12-week intervention, even after controlling for peak heart rate, respiratory exchange ratio, and fatigue.
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What it does not show
Only 27 participants, all from the HIIT arm of one trial; the authors note the sample may be underpowered for detecting associations. All participants were limited community ambulators with moderate walking impairment; the findings may not extend to people with more severe or less severe gait deficits. Only the treadmill portion of the session was analysed; the 20 minutes of overground walking were excluded to control for self-selected speed, so the cardiovascular cost of the full session is not captured. Percent HRR was averaged across the entire 20-minute treadmill block including passive recovery bouts, so a person with fast heart rate recovery would show a lower average than one with slow recovery, even if their burst intensity was the same. Loss of heart rate data across the 36 sessions reduced statistical power for the 12-week analysis. The step-length asymmetry association was specific to the first week and the particular HIIT protocol used; it did not persist across the full intervention.
The easy way to misread this
Do not read the step-length asymmetry finding as evidence that asymmetric gait is a training advantage. The authors suggest the higher heart rate may reflect reduced walking efficiency rather than a benefit. The association also disappeared across the full 12 weeks, so it does not predict long-term cardiovascular response, and with 27 participants the finding is hypothesis-generating rather than confirmatory.
Summarised by AI from the full paper, without a clinician reviewing it. Check it against the source before it changes what you do. Read it on PubMed →