RecruitingPhase 2Drug trialSGLT2i and KNO3 in HFpEF - The SAK HFpEF TrialThis study will test whether pharmacologic agents that may improve mitochondrial function and energy fuel metabolism \[Empagliflozin (Empa)\], with and without additional supplements that increase perfusion and fatty acid oxidation \[Potassium Nitrate (KNO3)\], improve submaximal exercise endurance and skeletal muscle oxidative phosphorylation capacity (SkM OxPhos) in participants with Heart Failure with Preserved Ejection Fraction (HFpEF).