Effect of home-based high-intensity interval training versus moderate-intensity continuous training in patients with myocardial infarction: a randomized controlled trial
Question
What are the effects of home-based HIIT compared with home-based moderate-intensity continuous training in patients with myocardial infarction?
Summary
This randomized trial compared two home-based exercise programs in stable myocardial infarction patients. Twice-weekly 12-week home HIIT and moderate continuous walking both improved 6-minute walk distance, blood pressure, resting heart rate, oxygen saturation, pulmonary function, respiratory and peripheral muscle strength, body composition, and quality of life measures. HIIT produced greater improvements than MICT in several pulmonary-function measures and knee extensor strength. The authors reported no adverse events during either intervention.
Methodology
- Clinically stable myocardial infarction patients, 3 months to 1 year post-MI, age 35-65, LVEF >50%, able to walk independently.
- 21 participants.
- Walking uphill, brisk walking, jogging, crouching, and going up/down front-side steps in the home environment.
- Work intervals: 4 minutes.
- Recovery: 3 minutes active recovery walking.
- Intensity: 85-95% HR reserve and RPE 15-18 for work intervals; recovery at 70% HR reserve and RPE <14.
- Approximately 48 minutes including 10-minute warm-up, 28-minute interval block, and 10-minute cool-down.
- 2 sessions/week on non-consecutive days.
- 12 weeks.
- Randomized controlled trial with two parallel home-based exercise groups.
- Functional capacity, Resting blood pressure and heart rate, Pulmonary function, and Respiratory muscle strength were tracked.
Outcomes
6-minute walk distance
Both HIIT and MICT significantly improved 6MWT distance, with no significant between-group difference.
HIIT 509.0 +/- 59.8 to 549.4 +/- 62.3 m, p=0.013; MICT 491.9 +/- 79.7 to 517.4 +/- 82.1 m, p=0.015; change difference p=0.386.
Blood pressure and resting heart rate
Both groups decreased resting systolic and diastolic BP and resting HR.
Between-group changes were not significant: SBP p=0.782, DBP p=0.435, HR p=0.731.
Pulmonary function
Both groups improved pulmonary function, and HIIT improved FEV1, FVC, and PEF more than MICT.
Between-group change p values: FEV1% predicted p=0.034, FVC% predicted p=0.002, PEF% predicted p=0.043.
Body composition
BMI and body fat percentage decreased in both groups; fat-free mass did not significantly change.
Between-group changes were not significant for BMI p=0.776 and body fat percentage p=0.287.
Peripheral muscle strength
Knee extensor and handgrip strength increased in both groups; knee extensor strength improved more in HIIT.
Knee extensor strength change HIIT +4.4 +/- 2.1 kg vs MICT +1.0 +/- 0.6 kg, between-group p<0.001; handgrip change p=0.070.
Health-related quality of life
HIIT improved physical, emotional, social, and global MacNew scores; MICT improved global score only; between-group changes were not significant.
MacNew global p=0.008 within HIIT and p<0.012 within MICT; between-group global change p=0.660.
Safety
No adverse events occurred during either exercise intervention.
Insights
- A home 4x4 HIIT format can be delivered with walking/step-based modalities when patients are screened, instructed, and monitored remotely.
- For functional capacity after MI, home HIIT did not outperform home MICT in 6MWT change, so HIIT claims should be outcome-specific.
- Combining HR reserve and RPE targets is a practical way to guide home intensity.
Limitations
- Small sample size.
- No no-exercise control group.
- Home exercise execution was not monitored in real time.
- Per-protocol analysis limits interpretation of adherence and effectiveness.
Safety
- No adverse events occurred during the exercise intervention in both groups.
- Patients received initial instruction on HR monitoring and target HR.
- Weekly phone counseling assessed problems related to exercise.