Short- and Long-Term Effects of High-Intensity Interval Training vs. Moderate-Intensity Continuous Training on Left
Prisca Eser1, Lukas D Trachsel1, Thimo Marcin1,2
1Department of Cardiology, Cardiovascular Centre, Inselspital, Bern University Hospital, University of Bern, Bern, Switzerland.
Insights
High-intensity interval training (HIIT) showed no short-term differences compared to moderate-intensity continuous training (MICT) in ST-segment elevation myocardial infarction (STEMI) patients. However, long-term follow-up revealed a potential worsening in left ventricular global longitudinal strain with HIIT.
Area of Science:
- Cardiology
- Exercise Physiology
Background:
- Limited evidence exists on high-intensity interval training (HIIT) safety and effectiveness post-ST-segment elevation myocardial infarction (STEMI).
- Guideline-directed medical therapy (GDMT) is standard for STEMI patients, but optimal exercise strategies require further investigation.
Purpose of the Study:
- To compare the short- and long-term effects of randomized HIIT versus moderate-intensity continuous training (MICT) on left ventricular (LV) remodeling markers in STEMI patients receiving GDMT.
Main Methods:
- A randomized controlled trial involving 73 male STEMI patients (<4 weeks post-MI) in a 12-week cardiac rehabilitation program.
- Patients underwent a 3-week run-in with MICT and GDMT up-titration, followed by 9 weeks of randomization to either HIIT or isocaloric MICT.
- Primary outcome: LV end-diastolic volume index (LVEDVi) at 12 weeks. Secondary outcomes: LV global longitudinal strain (GLS) and cardiorespiratory fitness at 3 weeks, 12 weeks, and 1-year follow-up.
Main Results:
- No significant group-by-time interaction for LVEDVi at the end of cardiac rehabilitation (p=0.557).
- A significantly smaller improvement in GLS was observed at 1-year follow-up in the HIIT group compared to the MICT group (p=0.031).
- Both groups showed significant improvements in cardiorespiratory fitness, with no significant group-by-time interactions at 12 weeks or 1 year.
Conclusions:
- In optimally treated STEMI patients, early HIIT demonstrated no short-term differences from isocaloric MICT regarding LVEDVi and cardiorespiratory fitness.
- The observed worsening in GLS at 1 year in the HIIT group warrants further investigation.
- Early HIIT may potentially offset long-term beneficial effects of GDMT on LV remodeling.
Aim:
Due to insufficient evidence on the safety and effectiveness of high-intensity interval training (HIIT) in patients early after ST-segment elevation myocardial infarction (STEMI), we aimed to compare short- and long-term effects of randomized HIIT or moderate-intensity continuous training (MICT) on markers of left ventricular (LV) remodeling in STEMI patients receiving optimal guideline-directed medical therapy (GDMT).
Materials And Methods:
Patients after STEMI (<4 weeks) enrolled in a 12-week cardiac rehabilitation (CR) program were recruited for this randomized controlled trial (NCT02627586). During a 3-week run-in period with three weekly MICT sessions, GDMT was up-titrated. Then, the patients were randomized to HIIT or isocaloric MICT for 9 weeks. Echocardiography and cardiopulmonary exercise tests were performed after run-in (3 weeks), end of CR (12 weeks), and at 1-year follow-up. The primary outcome was LV end-diastolic volume index (LVEDVi) at the end of CR. Secondary outcomes were LV global longitudinal strain (GLS) and cardiopulmonary fitness.
Results:
Seventy-three male patients were included, with the time between STEMI and start of CR and randomization being 12.5 ± 6.3 and 45.8 ± 10.8 days, respectively. Mixed models revealed no significant group × time interaction for LVEDVi at the end of CR (p = 0.557). However, there was a significantly smaller improvement in GLS at 1-year follow-up in the HIIT compared to the MICT group (p = 0.031 for group × time interaction). Cardiorespiratory fitness improved significantly from a median value of 26.5 (1st quartile 24.4; 3rd quartile 1.1) ml/kg/min at randomization in the HIIT and 27.7 (23.9; 31.6) ml/kg/min in the MICT group to 29.6 (25.3; 32.2) and 29.9 (26.1; 34.9) ml/kg/min at the end of CR and to 29.0 (26.6; 33.3) and 30.6 (26.0; 33.8) ml/kg/min at 1 year follow-up in HIIT and MICT patients, respectively, with no significant group × time interactions (p = 0.138 and 0.317).
Conclusion:
In optimally treated patients early after STEMI, HIIT was not different from isocaloric MICT with regard to short-term effects on LVEDVi and cardiorespiratory fitness. The worsening in GLS at 1 year in the HIIT group deserves further investigation, as early HIIT may offset the beneficial effects of GDMT on LV remodeling in the long term.
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