Fatty acid oxidation is a slower but more energy producing process than glycolysis, but glycolysis is a much faster process. In slow twitch muscle fibers (predominantly present in marathon runners, for example), complete glucose and fatty acid oxidation occurs, but in fast twitch muscle fibers (predominantly present in sprinters, for example), glycolysis predominates.  Glycolysis is upregulated and present in the heart (myocardium), pulmonary vasculature, immune cells, and bone marrow progenitor cells in PH. Is the heart (which primarily relies on fatty acid oxidation) in PH switching to glycolysis to compensate (i.e. to build muscle to compensate for increased afterload)?  Or