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Cited by 50Cardiovascular and exercise physiologyMuscle metabolism and nutritionSports Performance and Training

Effect of endurance training on muscle tca cycle metabolism during exercise in humans

Howarth, Krista R., LeBlanc, Paul J., Heigenhauser, George J. F., Gibala, Martin J.·2004·Journal of Applied Physiology
DOI 10.1152/japplphysiol.01344.2003
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Abstract

We tested the theory that links the capacity to perform prolonged exercise with the size of the muscle tricarboxylic acid (TCA) cycle intermediate (TCAI) pool. We hypothesized that endurance training would attenuate the exercise-induced increase in TCAI concentration ([TCAI]); however, the lower [TCAI] would not compromise cycle endurance capacity. Eight men (22 +/- 1 yr) cycled at approximately 80% of initial peak oxygen uptake before and after 7 wk of training (1 h/day, 5 days/wk). Biopsies (vastus lateralis) were obtained during both trials at rest, after 5 min, and at the point of exhaustion during the pretraining trial (42 +/- 6 min). A biopsy was also obtained at the end of exercise during the posttraining trial (91 +/- 6 min). In addition to improved performance, training increased (P < 0.05) peak oxygen uptake and citrate synthase maximal activity. The sum of four measured TCAI was similar between trials at rest but lower after 5 min of exercise posttraining [2.7 +/- 0.2 vs. 4.3 +/- 0.2 mmol/kg dry wt (P < 0.05)]. There was a clear dissociation between [TCAI] and endurance capacity because the [TCAI] at the point of exhaustion during the pretraining trial was not different between trials (posttraining: 2.9 +/- 0.2 vs. pretraining: 3.5 +/- 0.2 mmol/kg dry wt), and yet cycle endurance time more than doubled in the posttraining trial. Training also attenuated the exercise-induced decrease in glutamate concentration (posttraining: 4.5 +/- 0.7 vs. pretraining: 7.7 +/- 0.6 mmol/kg dry wt) and increase in alanine concentration (posttraining: 3.3 +/- 0.2 vs. pretraining: 5.6 +/- 0.3 mmol/kg dry wt; P < 0.05), which is consistent with reduced carbon flux through alanine aminotransferase. We conclude that, after aerobic training, cycle endurance capacity is not limited by a decrease in muscle [TCAI].

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Crossref · 10.1152/japplphysiol.01344.2003

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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 [185]

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Authors
Howarth, K. R., LeBlanc, P. J., Heigenhauser, G. J. F., & Gibala, M. J.
Affiliations
McMaster University (CA)
ORCID
Venue
Journal of Applied Physiology
Publisher
American Physiological Society
Published
2004-08
Volume
97
Issue
2
Pages
579-584
ISSN
  • 0161-7567 (ISSN-L)
  • 8750-7587
  • 1522-1601
DOI
10.1152/japplphysiol.01344.2003
OpenAlex
W2098276006
Cited by
50
References
30
Citations by year
2026: 3 · 2025: 2 · 2024: 5 · 2023: 2 · 2021: 4 · 2020: 1 · 2019: 3 · 2018: 2 · 2017: 1 · 2015: 2 · 2014: 4 · 2013: 1
FWCI
6.65
Type
journal article
Language
en
Open access
closed
Locations
  • Journal of Applied Physiology (publishedVersion)
  • PubMed (publishedVersion)
Funders
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 › Orthopedics and Sports Medicine › Sports Performance and Training
Keywords
endurance training, TCA cycle, TCA cycle intermediates, muscle metabolism, citrate synthase, glutamate, alanine, alanine aminotransferase, vastus lateralis, aerobic exercise, peak oxygen uptake
MeSH terms
Adult, Alanine Transaminase, Amino Acids, Blood Glucose, Citrate (si)-Synthase, Citric Acid Cycle, Glycogen, Heart Rate, Humans, Male, Oxygen Consumption, Physical Endurance, Exercise, Respiratory Mechanics, Muscle, Skeletal, Lactic Acid

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