PMID 37906165

Research
All papers

Effect of maximal-intensity and high-intensity interval training on exercise capacity and quality of life in patients with acute myocardial infarction: a randomized controlled trial

Nam H, Jeon HE, Kim WH, Joa KL, Lee H

Question

In low-to-moderate-risk patients after acute myocardial infarction, how do MIIT, HIIT, and usual care compare for exercise capacity, health-related quality of life, psychological symptoms, and safety during phase II cardiac rehabilitation?

Summary

This randomized controlled trial compared 9 weeks of hospital-based maximal-intensity interval training (MIIT), hospital-based high-intensity interval training (HIIT), and usual care in adults after acute myocardial infarction who were at low or moderate cardiac rehabilitation risk. MIIT improved VO2max more than HIIT and usual care, while both MIIT and HIIT improved health-related quality of life more than usual care. No heart-related adverse events were reported during the intervention, although three hospital-based participants reported pre-existing chronic musculoskeletal pain.

Methodology

  • Ninety-one adults after acute MI treated with primary PCI and classified as low or moderate cardiac rehabilitation risk.
  • 91 participants.
  • Treadmill aerobic interval training.
  • Work intervals: Four 4-minute intervals at 95-100% VO2max.
  • Recovery: 3-minute active rest at 60% VO2max.
  • Intensity: 95-100% VO2max during work intervals after adaptation.
  • 50 minutes.
  • Twice weekly.
  • 9 weeks.
  • Prospective, single-blinded, three-group pre-test/post-test randomized controlled study with a nonrandomized usual-care allocation based on participant preference for home or community exercise.
  • VO2max, MacNew Heart Disease HRQoL, 6-minute walking test, and Psychological and symptom questionnaires were tracked.

Outcomes

VO2max

VO2max improved in all groups, with MIIT greater than HIIT and usual care.

Time x group F=30.70, p<0.001; MD MIIT 7.85 (95% CI 6.65-9.05), HIIT 4.60 (3.16-6.03), usual care 1.41 (0.44-2.38); post-hoc a>b>c

Improved

MacNew global HRQoL

MIIT and HIIT improved MacNew global more than usual care.

F=4.99, p=0.010; MD MIIT 0.55 (0.35-0.75), HIIT 0.60 (0.43-0.77), usual care 0.24 (0.07-0.42); b=a>c

Improved

MacNew physical HRQoL

MIIT and HIIT improved MacNew physical more than usual care.

F=3.32, p=0.042; MD MIIT 0.66 (0.34-0.97), HIIT 0.58 (0.36-0.80), usual care 0.23 (0.01-0.48); a=b>c

Improved

MacNew emotional HRQoL

MIIT and HIIT improved MacNew emotional more than usual care.

F=4.56, p=0.013; post-hoc hospital-based groups greater than usual care

Improved

MacNew social HRQoL

No significant time x group interaction was observed for the social subdomain.

F=1.18, p=0.311

No clear change

6MWT

6MWT improved significantly in all groups; MIIT differed from usual care, while MIIT and HIIT did not differ.

HIIT MD 57.86 m (95% CI 37.06-78.66); usual care MD 18.84 m (8.58-29.11); HIIT vs MIIT p=0.148, HIIT vs usual care p=0.269, MIIT vs usual care p=0.002

Improved

Psychological outcomes

PHQ showed a significant time x group interaction with HIIT improving versus usual care, but FSS, PSQI, KASI, GAD, and PCL-5 had no significant interactions.

PHQ p=0.025; HIIT MD -2.21 (95% CI -3.58 to -0.83); FSS p=0.225, PSQI p=0.195, KASI p=0.360, GAD p=0.176, PCL-5 p=0.251

Mixed

Safety

No heart-related adverse events were reported in MIIT or HIIT during 9 weeks; three participants reported pre-existing chronic musculoskeletal pain.

No clear change

Insights

  • In medically screened, monitored post-MI cardiac rehabilitation, increasing 4x4 interval intensity from 85% to 95-100% VO2max produced larger VO2max gains over 9 weeks.
  • Both MIIT and HIIT improved HRQoL compared with usual care, suggesting hospital-based interval CR benefits extend beyond VO2max.
  • Safety findings are bounded by low-to-moderate cardiac risk, PCI-treated acute MI, clinical supervision, and continuous monitoring.

Limitations

  • Usual-care allocation was based on preference for home/community exercise rather than the same randomization process used for MIIT vs HIIT.
  • No follow-up assessment for long-term effects.
  • Specific low-to-moderate-risk post-MI population limits generalization to other recovery stages or high-risk patients.
  • Usual-care exercise compliance was not monitored.
  • Group-specific attendance and interval-completion fidelity were not reported.

Safety

  • No heart-related adverse events, including heart attack, ventricular tachycardia, recurrence of MI, or severe chest pain, were reported during the intervention period.
  • Two MIIT participants and one HIIT participant reported musculoskeletal pain, described as chronic pain that started before cardiac rehabilitation.
  • High-risk cardiac rehabilitation patients and those with exercise contraindications were excluded.