Effectiveness of Low -Versus High -Volume High -Intensity Interval Training in Patients With Chronic Heart Failure

This study compares two different amounts of high-intensity interval training (HIIT) — short bursts of intense exercise — in people with chronic heart failure. Researchers want to find out whether a lower-volume HIIT program works just as well as a higher-volume one, potentially making exercise more manageable for patients. **You may be eligible if...** - You are 18 years or older (male or female) - You have stable chronic heart failure with reduced heart pumping function (ejection fraction below 40%) - You are able to give informed consent **You may NOT be eligible if...** - You have had a heart attack within the last 2 days - You have unstable chest pain (angina) - You have uncontrolled dangerous heart rhythms - You have active heart infections (endocarditis, myocarditis, pericarditis) - You have severe aortic valve narrowing or decompensated heart failure - You have had a recent stroke or blood clot in the lungs - You have a physical disability that prevents safe exercise - You are in Class IV heart failure (unable to carry out any activity without symptoms) - You have very high blood pressure (over 200/110 mmHg) at rest Talk to your doctor to see if this trial is right for you.