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Maximal-intensity exercise does not fully restore muscle pyruvate dehydrogenase complex activation after 3 days of high-fat dietary intake
- Constantin-Teodosiu, D., Cederblad, G., Bergström, M., Greenhaff, P.L.
- Clinical nutrition 2019 v.38 no.2 pp. 948-953
- acetyl coenzyme A, biopsy, carnitine, excretion, exercise, fat intake, food intake, high fat diet, lactic acid, males, muscles, pyruvate dehydrogenase (lipoamide)
- Exercise activates muscle pyruvate dehydrogenase complex (PDC), but moderate intensity exercise fails to fully activate muscle PDC after high-fat diet . We investigated whether maximal intensity exercise overcomes this inhibition.Quadriceps femoris muscle biopsy samples were obtained from healthy males at rest, and after 46 and 92 electrically-evoked maximal intermittent isometric contractions, which were preceded by 3 days of either low- (18%) or high- (69%) isocaloric dietary fat intake (LFD and HFD, respectively).The ratio of PDCa (active form) to total PDCt (fully activated) at rest was 50% less after HFD (0.32 ± 0.01 vs 0.15 ± 0.01; P < 0.05). This ratio increased to 0.77 ± 0.06 after 46 contractions (P < 0.001) and to 0.98 ± 0.07 after 92 contractions (P < 0.001) in LFD. The corresponding values after HFD were less (0.54 ± 0.06; P < 0.01 and 0.70 ± 0.07; P < 0.01, respectively). Resting muscle acetyl-CoA and acetylcarnitine content was greater after HFD than LFD (both P < 0.05), but their rate of accumulation in the former was reduced during contraction. Muscle lactate content after 92 contractions was 30% greater after HFD (P < 0.05). Muscle force generation during contraction was no different between interventions, but HFD lengthened muscle relaxation time (P < 0.05). Daily urinary total carnitine excretion after HFD was 2.5-fold greater than after LFD (P < 0.01).A bout of maximal intense exercise did not overcome dietary fat-mediated inhibition of muscle pyruvate dehydrogenase complex activation, and was associated with greater muscle lactate accumulation, as a result of lower PDC flux, and increased muscle relaxation time.