This randomized controlled trial aims to compare the effects of High-Intensity Interval Training (HIIT) and Moderate-Intensity Continuous Training (MICT) in patients undergoing Phase II cardiac rehabilitation after coronary artery disease or post-angioplasty. A total of 66 participants will be randomly allocated into two groups: HIIT (n=33) and MICT (n=33). The intervention will be conducted 3 times per week using treadmill-based exercise protocols under heart rate monitoring. Primary outcomes include changes in left ventricular ejection fraction, functional capacity measured by 6-minute walk test, and lipid profile parameters before and after intervention. Secondary assessment includes health-related quality of life (HRQoL). The study aims to determine which exercise modality provides superior cardiovascular and functional improvement in stable cardiac patients during supervised rehabilitation.

This randomized controlled trial will compare the effects of High-Intensity Interval Training (HIIT) and Moderate-Intensity Continuous Training (MICT) in patients undergoing Phase II cardiac rehabilitation after stable coronary artery disease or post-angioplasty. A total of 66 participants will be randomly assigned into two groups.

The HIIT group will perform treadmill-based interval exercise 3 times per week at 85-95% heart rate reserve with active recovery periods, while the MICT group will perform continuous treadmill exercise at 65-75% heart rate reserve for 30-45 minutes.

Primary outcomes include left ventricular ejection fraction (echocardiography), functional capacity (6-minute walk test), and lipid profile (LDL, HDL, triglycerides, total cholesterol) measured before and after intervention. Health-related quality of life (HRQoL) will also be assessed. The study aims to determine which exercise protocol produces greater improvement in cardiac and functional outcomes.

Inclusion Criteria:

• Adults aged 18-60 years.
• Diagnosed with stable coronary artery disease confirmed by angiography, stress testing, or echocardiography.
• Left ventricular ejection fraction ≥45%.
• Functional NYHA Class I or II.
• Medically cleared by a cardiologist to participate in exercise (including recent ECG or stress test if necessary).
• Lightly active lifestyle prior to study (not involved in structured exercise programs).

Exclusion Criteria:

• Unstable angina or recent myocardial infarction (within the past 6 weeks).
• Uncontrolled hypertension (systolic BP >180 mmHg or diastolic BP >110 mmHg).
• Severe valvular heart disease, arrhythmias, or left ventricular dysfunction (EF <35%).
• Musculoskeletal disorders (e.g., severe osteoarthritis, recent fractures, or surgeries) preventing safe participation in exercise.
• Neurological disorders affecting mobility or safe exercise (e.g., stroke, Parkinson's disease).
• Uncontrolled diabetes mellitus (HbA1c >9% or recent hypoglycemia).
• Any other condition judged by the investigator to make participation unsafe.

This study is open-label because both participants and care providers are aware of the assigned exercise intervention. Outcome measurements will be recorded using standardized assessment tools including echocardiography, laboratory investigations, and 6-minute walk test.