The feasibility of implementing high-intensity interval training in cardiac rehabilitation settings: a retrospective analysis
Question
Is supervised HIIT feasible, acceptable, and safe in a real-world cardiac rehabilitation setting, and are there sex differences in feasibility outcomes?
Summary
In a retrospective analysis of 151 cardiac rehabilitation patients, a supervised 10-week group HIIT program using 4 x 4-min intervals was generally feasible and well received. Participants attended 16 +/- 5 of 20 classes, 73% attended at least 70% of classes, most met or exceeded HR targets, all questionnaire respondents were satisfied and found the program challenging, and 97% reported it felt safe. Three vasovagal episodes occurred and no delayed adverse events were reported.
Methodology
- 151 cardiac rehabilitation patients with CVD or CVD risk factors; 50 women and 101 men.
- 151 participants.
- Aerobic equipment or dance/movement-based HIIT.
- Work intervals: 4 min high-intensity interval.
- Recovery: 3 min lower-intensity interval.
- Intensity: 85-95% HRpeak for HI and 60-70% HRpeak for LO.
- 45 min including 10-min warm-up, 25-min interval block, and 10-min cool-down with resistance/stretching.
- 2 sessions/week.
- 10 weeks.
- Retrospective mixed-methods feasibility analysis of a clinical cardiac rehabilitation program
- Attendance and attrition, Intensity compliance, Patient experience, and Safety were tracked.
Outcomes
Attendance and attrition
Attendance was high and attrition was low overall, though women dropped out more often than men.
16 +/- 5 of 20 classes attended; 73% attended >=70%; dropouts 17/151 (11%); women 20% vs men 7%, p=0.034
Intensity compliance
Most participants met or exceeded HR targets, but many reported RPE below encouraged target ranges.
HI HR: 53% complied and 27% exceeded; LO HR: 42% complied and 42% exceeded; 58% below HI RPE target and 61% below LO RPE target
Patient experience
Questionnaire respondents perceived HIIT as difficult/challenging but satisfying and confidence-building.
RPE HI 14 +/- 2; RPE LO 10 +/- 2; difficulty 7 +/- 2; 100% challenging, 100% satisfied, 97% safe among respondents with available data
Safety
Three vasovagal episodes occurred, no delayed adverse events were reported, and most respondents perceived the program as safe.
3 events out of 2224 training sessions; no delayed adverse events; 97% reported safe
Insights
- In cardiac rehabilitation, HIIT feasibility depends on medical screening, HR monitoring, staff supervision, and accessible location.
- RPE alone may under-detect whether cardiac patients are reaching intended HR zones.
- A gradual post-interval intensity reduction may be important after high-intensity cardiac rehab intervals.
Limitations
- Retrospective single-center clinical program analysis.
- No comparator group.
- HR data were self-reported/recorded rather than downloaded from monitors.
- No data on compliance to exact interval durations.
- Feedback questionnaire data were available only in a subset.
- Male-predominant sample; sex comparisons should be interpreted cautiously.
Safety
- Three vasovagal episodes occurred early in the program; a step-by-step reduction in exercise intensity after high-intensity work bouts was implemented and no further vasovagal syncope was reported. No delayed adverse events were reported.