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Updated: Feb 14, 2026
A Chronic High-Intensity Interval Training and Diet-Induced Obesity Model to Maximize Exercise Effort and Induce Physiologic Changes in Rats
Published on: April 28, 2023
Maximal-intensity exercise does not fully restore muscle pyruvate dehydrogenase complex activation after 3 days of
D Constantin-Teodosiu1, G Cederblad2, M Bergström2
1MRC/ARUK Centre for Musculoskeletal Ageing Research, ARUK Centre for Sport, Exercise and Osteoarthritis, NIHR Nottingham BRC, School of Life Sciences, The Medical School, University of Nottingham, Queen's Medical Centre, Nottingham NG7 2UH, UK.
Background & Aims:
Exercise activates muscle pyruvate dehydrogenase complex (PDC), but moderate intensity exercise fails to fully activate muscle PDC after high-fat diet [1]. We investigated whether maximal intensity exercise overcomes this inhibition.
Methods:
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).
Results:
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).
Conclusions:
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.
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