Effects of High-Intensity Interval Training vs Moderate-Intensity Continuous Training on Body Composition and Blood Biomarkers in Coronary Artery Disease Patients: A Randomized Controlled Trial

Background: Cardiac rehabilitation (CR) is essential in reducing cardiovascular mortality and morbidity. High-intensity interval training (HIIT) has emerged as a promising exercise intervention for enhancing clinical outcomes in cardiac patients. This study aimed to investigate the effects of two short-term exercise-based programs employing HIIT and moderate-intensity continuous training (MICT) in comparison to a control group concerning blood pressure, body composition, and blood biomarkers in patients diagnosed with coronary artery disease (CAD). Methods: Seventy-two CAD patients (14% women) underwent randomization into three groups: HIIT, MICT, and control. The training programs encompassed six weeks of supervised treadmill exercises, conducted thrice weekly. MICT targeted approximate to 70-75% of peak heart rate (HRpeak), while HIIT was tailored to approximate to 85-95% of HRpeak. The control group received guidance on adopting healthy lifestyles. Outcome measurements included evaluations of blood pressure, body composition, and blood biomarkers. Results: In contrast to MICT, the HIIT exhibited superior improvements in body fat mass (Delta%HIIT: 4.5%, p < 0.001 vs. Delta%MICT: 3.2%, p <0.001), waist circumference (Delta%HIIT: 4.1%, p = 0.002 vs. Delta%MICT: 2.5%, p = 0.002), hemoglobin A1c (HbA1c) (Delta%HIIT: 10.4%, p < 0.001 vs. Delta%MICT: 32.3%, p < 0.001) and thyrotropin (TSH) (Delta%HIIT: 16.5%, p = 0.007 vs. Delta%MICT: 3.1%, p = 0.201). Both HIIT and MICT induced significant enhancements across all variables compared to the control group. Conclusions: HIIT and MICT emerged as effective modalities for enhancing systolic and diastolic function, body composition, and blood biomarkers in CAD patients, with HIIT demonstrating incremental improvements over MICT. The absence of participation in exercise-based programs following cardiovascular events yielded less favorable outcomes. HIIT holds promise as an adjunct intervention in CR programs for CAD patients.