About 50% or more of heart failure (HF) patients living in the community have preserved left ventricular ejection fraction (HFpEF), and the proportion is higher among women and the very elderly. A cardinal feature of HFpEF is reduced aerobic capacity, measured objectively as peak exercise pulmonary oxygen uptake (peak VO(2)), that results in decreased quality of life. Specifically, peak VO(2) of HFpEF patients is 30-70% lower than age-, sex-, and comorbidity-matched control patients without HF. The mechanisms for the reduced peak VO(2) are due to cardiovascular and skeletal muscle dysfunction that results in reduced oxygen delivery to and/or utilization by the active muscles. Currently, four randomized controlled exercise intervention trials have been performed in HFpEF patients. These studies have consistently demonstrated that 3-6 months of aerobic training performed alone or in combination with strength training is a safe and effective therapy to increase aerobic capacity and endurance and quality of life in HFpEF patients. Despite these benefits, the physiologic mechanisms underpinning the improvement in peak exercise performance have not been studied; therefore, future studies are required to determine the role of physical training to reverse the impaired cardiovascular and skeletal muscle function in HFpEF patients.