EXercise and Activin Inhibition to Modulate InflammatioN Effects on Heart Failure and Cognition (EXAMINE-HFC)

The goal of this clinical trial is to learn if therapy with activin ligand-trap biological therapy (an investigational drug) combined with exercise training can improve exercise capacity and cognitive function in heart failure with preserved ejection fraction (HFpEF). The main questions it aims to answer are: * Does activin-ligand trap biological therapy improve exercise capacity as measured by change in peak oxygen uptake (peak VO2) from baseline to week 12? * Does activin-ligand trap biological therapy improve cognitive function as assessed by the NIH-Toolbox Cognition Battery (NIHTB-CB) composite score and Rey Auditory Verbal Learning Test (RAVLT) from baseline to week 12? Researchers will compare activin-ligand trap biological therapy to a placebo (a look-alike substance that contains no drug) to see if activin-ligand trap therapy works to improve exercise capacity and cognitive function in patients with HFpEF.