Aerobic Exercise-induced Effect on Endothelial Function in Patients With Ischaemic Heart Disease

Inclusion Criteria: * Men and women aged between 45 and 75 years. * Diagnosed with acute myocardial infarction, unstable or stable angina. * Treated with percutaneous coronary intervention, coronary artery bypass grafting, or conservative treatment. * Event or intervention within 3 to 12 months prior to participation in the study. * Fluency in speaking and reading Spanish. * Residing in Elche or surrounding areas and able to attend evaluations and the exercise programme (not planning to be absent for more than one week during the programme). * Functional Class I-II according to the New York Heart Association (NYHA) classification. * No physical limitations for exercise. * Stable optimal medical treatment. * Physically inactive, defined as 1) not meeting the World Health Organization recommendations for both aerobic and strength exercise, and 2) not participating in a structured exercise programme at least 3 days per week for more than 3 months. Both conditions must be met for inclusion. Note: Casual walking is not considered grounds for exclusion. Exclusion Criteria: * Use of walking assistive devices. * Treatment with chemotherapy for any type of cancer in the past 2 years. * Hospitalisation in an intensive care unit in the past 6 months for reasons other than the ischaemic event. * Acute myocardial infarction group IV Killip-Kimball. * Obesity grade III (≥40.0 kg/m²). * Medical contraindication for inclusion in an exercise programme. * Diabetes with uncontrolled blood glucose levels. * Poorly controlled hypertension: resting blood pressure \> 180/110 mmHg. * Chest pain with exertion or ST-segment changes suggestive of residual ischemia during ergometry. Residual ischemia. * Severely reduced functional capacity on initial ergometry (\<5 metabolic equivalent of task). * Left ventricular ejection fraction less than 50%. * Severe stenosis of the left main coronary artery (\>50% significant disease). * Severe aortic stenosis, left ventricular outflow tract obstruction (e.g., obstructive hypertrophic cardiomyopathy) or aortic dissection. * Severe valvulopathy. * Acute pulmonary embolism or deep vein thrombosis. * Severe pulmonary hypertension. * Acute heart failure. * Acute endocarditis, myocarditis, or pericarditis. * Acute or chronic renal insufficiency (estimated glomerular filtration rate \<30 ml/min). * Pulmonary fibrosis or interstitial disease (severe respiratory insufficiency or confirmed chronic obstructive pulmonary disease). * Uncontrolled cardiac arrhythmias/hemodynamically unstable. * Permanent or persistent/paroxysmal atrial fibrillation with episodes in the past 6 months. * High-grade cardiac block. * Presence of implantable devices: cardiac resynchronization therapy pacemaker, implantable cardioverter defibrillators, or pacemaker. * Presence of ischaemic symptoms during the incremental exercise test performed before the intervention. * Severe autonomic or peripheral neuropathy. * Use of nitrates in pharmacological treatment. * Any planned surgical or medical intervention during the study period. * Plans to participate in or current participation in other studies that may interfere with this study. * Current pregnancy or intention to become pregnant during the study period.