The Role of High-Intensity Interval Training (HIIT) vs. Moderate-Intensity Continuous Training (MICT) in Improving Cardiovascular Fitness in Patients with Coronary Artery Disease

Background: Exercise is a crucial component of cardiac rehabilitation for patients with Coronary Artery Disease (CAD). High-Intensity Interval Training (HIIT) and Moderate-Intensity Continuous Training (MICT) are two commonly used exercise modalities, but their comparative effectiveness in improving cardiovascular fitness in CAD patients remains uncertain.Objective: To compare the effects of HIIT and MICT on cardiovascular fitness in patients with CAD.Methods: A randomized controlled trial was conducted at Therapy Plus Clinics, Architect Society, Lahore, Pakistan, with 44 participants (22 in each group). Participants were randomly assigned to either HIIT or MICT for a 12-week intervention. Cardiovascular fitness was assessed using VO₂ max, resting heart rate, and blood pressure measurements before and after the intervention. Data analysis was performed to compare the outcomes between the two groups.Results: The HIIT group showed a significant improvement in VO₂ max (25.2 ± 3.5 to 30.4 ± 4.2 mL/kg/min) compared to the MICT group (24.8 ± 3.7 to 27.2 ± 3.9 mL/kg/min, p = 0.01). Additionally, the HIIT group experienced a greater reduction in resting heart rate (72.5 ± 8.2 to 68.1 ± 7.9 bpm) compared to the MICT group (73.2 ± 7.8 to 70.3 ± 7.5 bpm, p = 0.04). Both groups showed reductions in systolic and diastolic blood pressures, but the differences were not statistically significant.Conclusion: HIIT appears to be more effective than MICT in improving cardiovascular fitness, as evidenced by greater enhancements in VO₂ max and reductions in resting heart rate. These findings suggest that HIIT may be a superior exercise modality for CAD patients, offering a time-efficient alternative to traditional moderate-intensity exercise. Further research is needed to explore long-term effects and broader applicability.