Abstract
A lag in the increase in oxygen consumption (MO 2 ) 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.