Tricarboxylic acid cycle intermediate pool size and estimated cycle flux in human muscle during exercise
Abstract
We examined the relationship between tricarboxylic acid (TCA) cycle intermediate (TCAI) pool size, TCA cycle flux (calculated from leg O 2 uptake), and pyruvate dehydrogenase activity (PDH a) in human skeletal muscle. Six males performed moderate leg extensor exercise for 10 min, followed immediately by intense exercise until exhaustion (3.8 ± 0.5 min). The sum of seven measured TCAI (ΣTCAI) increased ( P ≤ 0.05) from 1.39 ± 0.11 at rest to 2.88 ± 0.31 after 10 min and to 5.38 ± 0.31 mmol/kg dry wt at exhaustion. TCA cycle flux increased ∼70-fold during submaximal exercise and was ∼100-fold higher than rest at exhaustion. PDH a corresponded to 77 and 90% of TCA cycle flux during submaximal and maximal exercise, respectively. The present data demonstrate that a tremendous increase in TCA cycle flux can occur in skeletal muscle despite a relatively small change in TCAI pool size. It is suggested that the increase in ΣTCAI during exercise may primarily reflect an imbalance between the rate of pyruvate production and its rate of oxidation in the TCA cycle.
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The role of protein metabolism during exercise has been linked to the provision of precursors for tricarboxylic acid (TCA) reaction; a major common pathway for the oxidation of carbohydrates, fats and amino acids.
“The role of protein metabolism during exercise has also been linked to the provision of precursors for tricarboxylic acid (TCA) reaction; a major common pathway for the oxidation of carbohydrates, fats and amino acids [180,181].”
From Regulation of Energy Substrate Metabolism in Endurance Exercise (2021) · cites this paper as [180]
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Self-citationDawson, K. D., Baker, D. J., Greenhaff, P. L., & Gibala, M. J. (2005) · The Journal of Physiology · doi:10.1113/jphysiol.2004.079939 · Cited by 21 · see citing works
Self-citation
- Authors
- Gibala, M. J., MacLean, D. A., Graham, T. E., & Saltin, B.
- Affiliations
- Rigshospitalet (DK)
- University of Guelph (CA)
- ORCID
- Gibala, Martin J.
- Venue
- American Journal of Physiology-Endocrinology and Metabolism
- Publisher
- American Physiological Society
- Published
- 1998-08-01
- Volume
- 275
- Issue
- 2
- Pages
- E235-E242
- ISSN
- 0193-1849 (ISSN-L)
- 1522-1555
- OpenAlex
- W2182595322
- Cited by
- 160
- References
- 1
- Citations by year
- 2026: 4 · 2025: 9 · 2024: 10 · 2023: 4 · 2022: 8 · 2021: 9 · 2020: 5 · 2019: 7 · 2018: 6 · 2017: 8 · 2016: 4 · 2015: 3 · 2014: 5 · 2013: 6 · 2012: 5
- FWCI
- 9.89
- Type
- journal article
- Language
- en
- Open access
- closed
- Locations
- American Journal of Physiology-Endocrinology and Metabolism (publishedVersion)
- PubMed (publishedVersion)
- 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
- TCA cycle, TCA cycle intermediates, TCA cycle flux, skeletal muscle, physical activity, pyruvate oxidation, oxygen consumption
- MeSH terms
- Adult, Alanine, Ammonia, Carboxylic Acids, Citric Acid Cycle, Physical Exertion, Glutamine, Heart Rate, Humans, Lactates, Male, Oxygen Consumption, Regional Blood Flow, Time Factors, Exercise, Muscle, Skeletal, Glutamic Acid
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