No acetyl group deficit is evident at the onset of exercise at 90% of maximal oxygen uptake in humans

Marwood, Simon and Constantin-Teodosiu, Dumitru and Casey, Edel and Whyte, Martin and Boobis, Leslie and Bowtell, Jo (2010) No acetyl group deficit is evident at the onset of exercise at 90% of maximal oxygen uptake in humans. Journal of Sports Sciences, 28 (3). pp. 267-279. ISSN 0264-0414

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The existence of an acetyl group deficit at or above 90% of maximal oxygen uptake ([Vdot]O2max) has proved controversial, with contradictory results likely relating to limitations in previous research. The purpose of the present study was to determine whether the “acetyl group deficit” occurs at the start of exercise at 90%[Vdot]O2max in a well-controlled study. Eight male participants (age: 33.6 ± 2.0 years; [Vdot]O2max: 3.60 ± 0.21 litres · min−1) completed two exercise bouts at 90%[Vdot]O2max for 3 min following either 30 min of saline (control) or dichloroacetate (50 mg · kg−1 body mass) infusion, ending 15 min before exercise. Muscle biopsies were obtained immediately before and after exercise while continuous non-invasive measures of pulmonary oxygen uptake and muscle deoxygenation were made. Muscle pyruvate dehydrogenase activity was significantly higher before exercise following dichloroacetate infusion (control: 2.67 ± 0.98 vs. dichloroacetate: 17.9 ± 1.1 mmol acetyl-CoA · min−1 · mg−1 protein, P = 0.01) and resulted in higher pre- and post-exercise muscle acetylcarnitine (pre-exercise control: 3.3 ± 0.95 vs. pre-exercise dichloroacetate: 8.0 ± 0.88 vs. post-exercise control: 11.9 ± 1.1 vs. post-exercise dichloroacetate: 17.2 ± 1.1 mmol · kg−1 dry muscle, P < 0.05). However, substrate-level phosphorylation (control: 125 ± 20 vs. dichloroacetate: 113 ± 13 mmol adenosine triphosphate · kg−1 dry muscle) and [Vdot]O2 kinetics (control: 19.2 ± 2.2 vs. dichloroacetate: 22.8 ± 2.5 s), were unaltered. Furthermore, dichloroacetate infusion blunted the slow component of [Vdot]O2 and muscle deoxygenation and slowed muscle deoxygenation kinetics, possibly by enhancing oxygen delivery during exercise. These data support the hypothesis that the “acetyl group deficit” does not occur at or above 90%[Vdot]O2max.

Item Type: Article
Additional Information and Comments: This is an Author's Original Manuscript of an article submitted for consideration in Journal of Sports Sciences, [copyright Taylor & Francis]; Journal title is available online at
Keywords: Acetyl group deficit, dichloroacetate, exercise, near infrared spectroscopy, muscle deoxygenation kinetics, oxygen uptake kinetics
Subjects: Q Science > QP Physiology
Faculty / Department: Faculty of Science > School of Health Sciences
Depositing User: Susan Murray
Date Deposited: 06 Mar 2014 17:05
Last Modified: 06 Mar 2014 17:05

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