This study is being done because investigators are trying to determine how respiratory muscle and lung function influence the exercise responses in heart failure and healthy participants. Further, the heart failure patients will participate in an intervention to improve their respiratory muscle function to determine if this improves exercise capacity.

The participants enrolled in this study will be asked to make 4 or 9 separate study visits. Healthy participants will perform 4 study visits and heart failure participants will perform 9 study visits.

During study visit 1, the participants will be asked to get a DEXA bone scan, perform pulmonary function tests, and exercise on a stationary bike at maximal exertion while breathing into a mouth piece. During the exercise test, a iodine-based dye will be injected via a venous catheter in the arm. Also, a thin balloon will be inserted through the nose into the esophagus.

During study visit 2, the participants will breathe the same way they did during exercise, but will be seated and not exercising. A thin balloon will be inserted through the nose into the esophagus.

During study visits 3 and 4, the participants will perform different respiratory muscle workouts at rest that will be at different intensities ranging from very easy to moderate for ~10 minutes. An iodine-based dye will be injected via a venous catheter in the arm.

The participant's with heart failure will then perform 8 weeks of breathing muscle training at home. After 3 weeks of breathing muscle training, the participants will return for study visit 5 where the training load will be adjusted. Following the 8 weeks of breathing muscle training, the heart failure participants will perform the same 4 study visits as outlined above.

Healthy subjects: Adults (≥21 years of age) in the absence of a history of HFpEF or HFrEF, pulmonary, neurologic, orthopedic, or other diseases affecting the neuromuscular system. Controls will be matched for age and sex.

All HFpEF patients will be managed by their primary care physician or cardiologist with additional review and oversight by Dr. Borlaug (Co-Investigator) prior to enrollment to ensure adequacy of inclusion and exclusion criteria and that participation in exercise testing and resistance exercise training is safe.

Inclusion Criteria for HFpEF, includes:

• Clinical diagnosis of HFpEF.
• Patients with a history stable (no medication changes in past 6 weeks (w/duration of diagnosis >6 months).
• New York Heart Association class I-III.
• Current non-smokers with <15 pack year history.
• Non-pregnant women, and individuals who are able to exercise (i.e. without orthopedic limitations or neuromuscular disorders).

Exclusion Criteria for all subjects, includes:

• history of dangerous arrhythmias
• body mass index >35 kg/m2
• current smokers and/or smoking history >15 pack years
• pregnant women
• uremia, history of allergy to iodides
• impaired renal function
• creatinine value greater than or equal to 1.3 mg/dL (via clinical record within the past 6 months)
• diagnosis of liver disease
• individuals who are not able to engage in exercise