The pyruvate dehydrogenase complex occupies a central and strategic posi-tion in muscle intermediary metabolism and is primarily regulated by phos-phorylation⁄dephosphorylation. The identification of multiple isoforms of pyruvate dehydrogenase kinase (PDK1–4) and pyruvate dehydrogenase phosphatase (PDP1–2) has raised intriguing new possibilities for chronic pyruvate dehydrogenase complex control.