The purpose of this study is to understand if breathing muscle training combined with cardiac rehabilitation influences the blood flow and blood pressure response during exercise.

Inclusion Criteria - Heart Failure Group:

• Adult 18 years and older.
• English speaking.
• Has a qualifying heart failure indication for center-based cardiac rehabilitation.

Inclusion Criteria - Healthy Control Group:

• Adult 18 years and older.
• English speaking.
• Absence of pulmonary, cardiovascular, musculoskeletal, neurologic, or orthopedic diseases. Controls will be matched for age and sex.

Exclusion Criteria:

• HF patients who are unable to engage in a regularly structured exercise training program as part of a clinically indicated center-based outpatient cardiac rehabilitation program.
• Participants unable/unwilling to provide informed consent.
• Uremia, history of allergy to iodides. Impaired renal function.
• Creatinine value greater than 1.3 mg/dL (via clinical record within the past 6 months).
• Diagnosis of liver disease.