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Cited by 45Cardiovascular and exercise physiologyMuscle metabolism and nutritionExercise and Physiological Responses

Dissociation between muscle tricarboxylic acid cycle pool size and aerobic energy provision during prolonged exercise in humans

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Gibala, Martin J., González‐Alonso, José, Saltin, Bengt·2002·The Journal of Physiology
DOI 10.1113/jphysiol.2002.028084PMC PMC2290699
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Abstract

It has been suggested that a decrease in the total concentration of tricarboxylic acid cycle intermediates (TCAIs)--secondary to a reduction in glycogen availability--compromises oxidative energy provision in skeletal muscle during prolonged exercise. However, no study has directly tested this hypothesis. We therefore studied six men (28 +/- 2 years) during 90 min of leg kicking exercise at an intensity equivalent to 70 % of maximum. Biopsies (vastus lateralis) were obtained at rest and after 5, 10, 15, 30, 60 and 90 min of exercise, and thigh oxygen uptake (V(O(2),thigh)) was calculated according to the Fick principle. The sum of six measured TCAIs (approximately 95 % of total pool size) was 1.30 +/- 0.15 mmol (kg dry wt)(-1) at rest and increased (P < or = 0.05) rapidly during exercise to a peak value of 3.15 +/- 0.23 mmol (kg dry wt)(-1) after 10 min. Thereafter, the [TCAI] declined to 2.14 +/- 0.23, 1.73 +/- 0.32 and 1.62 +/- 0.10 mmol (kg dry wt)(-1) after 30, 60 and 90 min, respectively (P < or = 0.05 vs.10 min). Despite the 50 % decrease in [TCAI], aerobic energy provision was not compromised, as evidenced by stable V(O(2),thigh) values throughout the entire exercise bout and little change in muscle [phosphocreatine] after 10 min. The largest decrease in [TCAI] (delta = 1.00 +/- 0.24 mmol (kg dry wt)(-1)) occurred from 10 to 30 min of exercise despite the fact that muscle [glycogen] remained relatively high at this point in exercise (approximately 274 +/- 24 mmol (kg dry wt)(-1) after 30 min; approximately 65 % of rest value). Conversely, there was little change in [TCAI] during the final 30 min of exercise (delta = 0.11 +/- 0.29 mmol (kg dry wt)(-1)) despite a decrease in [glycogen] to approximately 72 +/- 3 mmol (kg dry wt)(-1) after 90 min (approximately 13 % of rest value). We conclude that there is a progressive decrease in muscle [TCAI] during prolonged exercise in humans; however this decrease does not compromise aerobic energy provision and is not attributable to the depletion of muscle [glycogen].

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  • In humans, a dissociation between TCA cycle pool size and aerobic phosphorylation was demonstrated, suggesting that TCA intermediate content does not represent any functional importance to oxidative phosphorylation.

    “In humans, a dissociation between TCA cycle pool size and aerobic phosphorylation was demonstrated [184,185], suggesting that TCA intermediate content does not represent any functional importance to oxidative phosphorylation [182].”

    From Regulation of Energy Substrate Metabolism in Endurance Exercise (2021) · cites this paper as [184]

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Authors
Gibala, M. J., González‐Alonso, J., & Saltin, B.
Affiliations
Rigshospitalet (DK)
Corresponding author
Gibala, Martin J.
ORCID
Venue
The Journal of Physiology
Publisher
Wiley
Published
2002-12
Volume
545
Issue
2
Pages
705-713
ISSN
  • 0022-3751 (ISSN-L)
  • 1469-7793
DOI
10.1113/jphysiol.2002.028084
PMC
PMC2290699
OpenAlex
W1996146747
Cited by
45
References
36
Citations by year
2026: 3 · 2025: 3 · 2024: 3 · 2023: 1 · 2021: 1 · 2018: 1 · 2017: 1 · 2014: 1 · 2013: 2
FWCI
7.61
Type
journal article
Language
en
Open access
Licence
onlinelibrary.wiley.com/termsAndConditions#vor (vor)
Locations
  • The Journal of Physiology (publishedVersion)
  • PubMed Central (publishedVersion)
  • PubMed (publishedVersion)
Funders
  • Danmarks Grundforskningsfond
  • Natural Sciences and Engineering Research Council of Canada
Topics
  • Health Sciences › Medicine › Complementary and alternative medicine › Cardiovascular and exercise physiology
  • Life Sciences › Biochemistry, Genetics and Molecular Biology › Cell Biology › Muscle metabolism and nutrition
  • Health Sciences › Medicine › Rehabilitation › Exercise and Physiological Responses
Keywords
tricarboxylic acid cycle intermediates, prolonged exercise, skeletal muscle, muscle glycogen, phosphocreatine, oxidative metabolism, vastus lateralis, glycogen depletion, muscle energy metabolism, substrate utilization, substrate oxidation
MeSH terms
Adult, Aerobiosis, Alanine, Carbon Dioxide, Citric Acid Cycle, Energy Metabolism, Glycogen, Humans, Male, Oxygen Consumption, Exercise, Respiratory Mechanics, Muscle, Skeletal, Glutamic Acid

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