The Inorganic Nitrate and eXercise Performance in Heart Failure (iNIX-HF)

This trial is testing whether inorganic nitrate supplements (found naturally in beets and leafy greens) can improve exercise capacity in people with heart failure with reduced ejection fraction — a condition where the heart muscle is weakened and pumps less blood than it should. Participants will undergo exercise testing to measure improvement. **You may be eligible if...** - You have heart failure with a reduced pumping function (ejection fraction below 45%) - Your heart failure is classified as moderate (NYHA Class II or III) - Your heart medications have been stable for at least 60 days **You may NOT be eligible if...** - You are a prisoner, a child, or in another vulnerable category - You took organic nitrate therapy (like nitroglycerin) in the past 3 months - You have a major orthopedic, psychiatric, or neurological condition that prevents exercise testing - Your kidney filtration rate is below 45 mL/min - Your blood pressure is too low or too high at screening - You use medications for erectile dysfunction (phosphodiesterase inhibitors) and are unwilling to stop - Your ejection fraction is 45% or higher - You have certain heart conditions (hypertrophic cardiomyopathy, amyloid, active myocarditis, complex congenital heart disease) - You have severe liver disease or another terminal illness Talk to your doctor to see if this trial is right for you.