Dichloroacetate (DCA) reveals the presence of metabolic inertia at the start of exercise in rainbow trout (Oncorhynchus mykiss, Walbaum 1792).

A lag in the increase in oxygen consumption (MO2) occurs at the start of sustainable exercise in trout. Waterborne dichloroacetate (0.58 and 3.49 mmol l(-1)), a compound which activates pyruvate dehydrogenase (PDH) by inhibiting PDH kinase in muscle, accelerates the increase in MO(2)during the first 10 min of sustainable exercise when velocity is elevated to 75% critical swimming speed in a swim tunnel. There are no effects on MO(2)thereafter or at rest. This indicates that a delay in PDH activation ("metabolic inertia") contributes to the lag phenomenon.