Pyruvate dehydrogenase activation in inactive muscle during and after maximal exercise in men

Pyruvate dehydrogenase activity (PDH ) and acetyl-group accumulation were examined in the inactive deltoid muscle in response to maximal leg exercise in men. Seven subjects completed three consecutive 30-s bouts of maximal isokinetic cycling, with 4-min rest intervals between bouts. Biopsies of the deltoid were obtained before exercise, after bouts 1 and 3, and after 15 min of rest recovery. Inactive muscle lactate (LA) and pyruvate (PYR) contents increased more than twofold ( P < 0.05) after exercise ( bout 3) and remained elevated after 15 min of recovery ( P < 0.05). Increased PYR accumulation secondary to LA uptake by the inactive deltoid was associated with greater PDH , which progressively increased from 0.71 ± 0.23 mmol ⋅ min ⋅ kg wet wt at rest to a maximum of 1.83 ± 0.30 mmol ⋅ min ⋅ kg wet wt after bout 3( P < 0.05) and remained elevated after 15 min of recovery (1.63 ± 0.24 mmol ⋅ min ⋅ kg wet wt ; P < 0.05). Acetyl-CoA and acetylcarnitine accumulations were unaltered. Increased PDH allowed and did not limit the oxidation of LA and PYR in inactive human skeletal muscle after maximal exercise.