This research in Veterans with heart failure with preserved ejection fraction (HFpEF) will provide new information on the mechanisms determining the patients' exercise intolerance and the efficacy of regular physical activity to improve this shortcoming by alleviating the patients' neurocirculatory abnormalities. Specifically, the investigators will focus on the role of nerves originating in working limb muscles in determining the patients' exercise intolerance and compromised fatigue resistance before and after a chronic exercise intervention. By focusing on a specific mechanism, this project will evaluate the validity of exercise as an alternative treatment strategy with the overall purpose of improving the quality of life of Veterans with HFpEF.