Fig. 1

Proposed interaction within skeletal muscle between fatty acid metabolism and glycolysis during high intensity exercise. During high intensity exercise the high glycolytic rate will produce high amounts of acetyl CoA which will exceed the rate of the TCA cycle. Free carnitine acts as an acceptor of the glycolysis derived acetyl groups forming acetylcarnitine, mediated by carnitine acyltransferase (CAT). Due to the reduced carnitine, the substrate for CPT-1 forming FA acylcarnitine will be reduced limiting FA transport into the mitochondrial matrix. This limits B-oxidation potential reducing overall FAox. OMM: outer mitochondrial membrane; IMM: inner mitochondrial membrane; CPT-1: carnitine pamitoyltransferase; FA: fatty acid; CPT-II: carnitine palmitoyltransferase II; PDH: pyruvate dehydrogenase; CAT: carnitine acyltransferase. Adapted from Jeppesen and Kiens 2012