Exercise Intolerance in Heart Failure

This study is investigating the specific physiological reasons why people with heart failure — a condition where the heart cannot pump blood effectively — struggle to exercise. Researchers will monitor heart, lung, and muscle function carefully during physical activity to identify which components of the cardiovascular and respiratory systems are most responsible for limiting exercise capacity. Understanding these mechanisms could lead to more targeted treatments that help heart failure patients become more active and improve their quality of life. **You may be eligible if...** - You are over 21 years of age (any gender), with no upper age limit - Your treating cardiologist has approved your participation - You have had a confirmed diagnosis of heart failure with NYHA Class II or III symptoms (meaning you have symptoms during regular or mild physical activity) for at least one month - Your heart's pumping function has been formally measured **You may NOT be eligible if...** - You have unstable heart failure or have been recently hospitalized for heart problems - You have other severe medical conditions that make exercise testing unsafe - Your physician does not approve your participation Talk to your doctor to see if this trial is right for you.