High-fat diet (HFD) inhibits the mitochondrial pyruvate dehydrogenase complex (PDC)-controlled carbohydrate (CHO) oxidation, contributing to muscle insulin resistance, which is an underlying cause of chronic elevation in blood glucose concentration and metabolic inflexability in type 2 diabetes. Conversely, muscle contraction increases simultaneously CHO-derived pyruvate generation and pyruvate oxidation by enhancing glycogenolysis and leg glucose uptake and by increasing the amount of active mitochondrial PDC, respectively. The activation of muscle PDC during muscle contraction is achieved by the accumulation of mitochondrial calcium and pyruvate. They function by activating two phosphatases (PDP1 and 2) and inhibiting two kinases (PDK2 and 4 - the most prevalent isoforms in muscle), respectively, and jointly appear to be able to fully activate PDC at exercise intensities of 75% maximal oxygen consumption and above. Nevertheless, when exercise at this workload is preceded by several days of HFD intake, calcium and pyruvate seem unable to activate PDC to the same extent as in the control condition resulting in reduced CHO oxidation compared to control at exercise intensities where muscle glycogen is an important contributor to energy production. We have recently revealed molecular (i.e. FOXO1) and biochemical changes underpinning this process in human quadriceps muscle biopsies samples collected at rest and during different models of exercise (electrically evoked maximal intermittent isometric contraction and sub-maximal intensity cycling at 75% of VO2 max) following three days of HFD. We also showed in humans that activation of PDC using dichloroacetate, which is a more potent pharmacological inhibitor of PDK2 and 4 proteins than pyruvate, overrides these diet-induced changes and restores the HFD-mediated inhibition of CHO oxidation during exercise.