A Study to Evaluate Breathing Muscle Training in Cardiac Rehab

This study is testing whether adding breathing muscle training exercises to standard cardiac rehabilitation improves outcomes for heart failure patients. It also enrolls healthy volunteers to establish normal reference values. **You may be eligible if...** - You are 18 or older and English-speaking - You have heart failure and have been referred to an outpatient cardiac rehabilitation program, OR - You are a healthy adult without known heart, lung, muscle, nerve, or bone conditions **You may NOT be eligible if...** - You are a heart failure patient unable to participate in a structured exercise program - You have kidney disease (creatinine above 1.3 mg/dL) or liver disease - You have a history of allergy to iodine-based contrast or uremia - You are unable or unwilling to give consent Talk to your doctor to see if this trial is right for you.