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Cited by 167Muscle metabolism and nutritionSports Performance and TrainingCardiovascular and exercise physiology

Daily training with high carbohydrate availability increases exogenous carbohydrate oxidation during endurance cycling

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Cox, Gregory R., Clark, Sally A., Cox, Amanda J., Halson, Shona L., Hargreaves, Mark, Hawley, John A., Jeacocke, Nikki, Snow, Rodney J. +2 more·2010·Journal of Applied Physiology
DOI 10.1152/japplphysiol.00950.2009
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Abstract

We determined the effects of varying daily carbohydrate intake by providing or withholding carbohydrate during daily training on endurance performance, whole body rates of substrate oxidation, and selected mitochondrial enzymes. Sixteen endurance-trained cyclists or triathletes were pair matched and randomly allocated to either a high-carbohydrate group (High group; n = 8) or an energy-matched low-carbohydrate group (Low group; n = 8) for 28 days. Immediately before study commencement and during the final 5 days, subjects undertook a 5-day test block in which they completed an exercise trial consisting of a 100 min of steady-state cycling (100SS) followed by a 7-kJ/kg time trial on two occasions separated by 72 h. In a counterbalanced design, subjects consumed either water (water trial) or a 10% glucose solution (glucose trial) throughout the exercise trial. A muscle biopsy was taken from the vastus lateralis muscle on day 1 of the first test block, and rates of substrate oxidation were determined throughout 100SS. Training induced a marked increase in maximal citrate synthase activity after the intervention in the High group (27 vs. 34 μmol·g−1·min−1, P < 0.001). Tracer-derived estimates of exogenous glucose oxidation during 100SS in the glucose trial increased from 54.6 to 63.6 g ( P < 0.01) in the High group with no change in the Low group. Cycling performance improved by ∼6% after training. We conclude that altering total daily carbohydrate intake by providing or withholding carbohydrate during daily training in trained athletes results in differences in selected metabolic adaptations to exercise, including the oxidation of exogenous carbohydrate. However, these metabolic changes do not alter the training-induced magnitude of increase in exercise performance.

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Crossref · 10.1152/japplphysiol.00950.2009

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  • Regular exposure to high carbohydrate loads may upregulate SGLT1 expression, enhance intestinal absorptive capacity, reduce GI distress, and ultimately increase the capacity for exogenous carbohydrate oxidation.

    “Regular exposure to high carbohydrate loads may upregulate SGLT1 expression, enhance intestinal absorptive capacity, reduce GI distress, and ultimately increase the capacity for exogenous carbohydrate oxidation [74, 75, 76].”

    From Carbohydrate Storage and Supplementation Strategies for Peak Performance in Cross-Country Skiing (2026) · cites this paper as [75]

  • A high-carbohydrate diet increases the number of sodium glucose co-transporter transporters in the intestine and their activity, allowing greater carbohydrate absorption and oxidation during exercise.

    “For example, a high-carbohydrate diet will increase the number of sodium glucose co-transporter transporters in the intestine as well as the activity of the transporters [75–78], allowing greater carbohydrate absorption and oxidation during exercise [74].”

    From Periodized Nutrition for Athletes (2017) · cites this paper as [74]

  • Diet has an impact on the capacity of the intestine to absorb nutrients.

    “There is also evidence that diet has an impact on the capacity of the intestine to absorb nutrients [74].”

    From Periodized Nutrition for Athletes (2017) · cites this paper as [74]

  • Potential pitfalls to long-term training with low carbohydrate availability include perturbations to immune function, impaired training intensity, reduced ability to oxidise exogenous carbohydrate during competition and increased muscle protein oxidation.

    “Despite the theoretical rationale for the training-low paradigm, potential pitfalls to longterm training with low CHO availability include perturbations to immune function [67] impaired training intensity [55], reduced ability to oxidise exogenous CHO during competition [68] and increased muscle protein oxidation [69].”

    From New strategies in sport nutrition to increase exercise performance (2016) · cites this paper as [68]

  • Habituation to a high CHO diet enhances total carbohydrate oxidation rates.

    “It is apparent that well-trained athletes can tolerate higher intakes of CHO during running [128], and that habituation to a high CHO diet enhances total carbohydrate oxidation rates which may be important for sustained race performance [141] and reduced GI upset.”

    From International Society of Sports Nutrition Position Stand: nutritional considerations for single-stage ultra-marathon training and racing (2019) · cites this paper as [141]

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Authors
Cox, G. R., Clark, S. A., Cox, A. J., Halson, S. L., Hargreaves, M., Hawley, J. A., Jeacocke, N., Snow, R. J., Yeo, W. K., & Burke, L. M.
Affiliations
  • Deakin University (AU)
  • Physiology, Australian Institute of Sport, Belconnen;
  • University of Newcastle Australia (AU)
  • The University of Melbourne (AU)
  • RMIT University (AU)
  • Sports Nutrition, Australian Institute of Sport, Belconnen;
Corresponding author
Cox, Gregory R.
ORCID
Venue
Journal of Applied Physiology
Publisher
American Physiological Society
Published
2010-07
Volume
109
Issue
1
Pages
126-134
ISSN
  • 0161-7567 (ISSN-L)
  • 8750-7587
  • 1522-1601
DOI
10.1152/japplphysiol.00950.2009
OpenAlex
W2092809716
Cited by
165
References
47
Citations by year
2026: 4 · 2025: 11 · 2024: 4 · 2023: 6 · 2022: 5 · 2021: 12 · 2020: 11 · 2019: 19 · 2018: 8 · 2017: 11 · 2016: 13 · 2015: 7 · 2014: 14 · 2013: 19 · 2012: 9
FWCI
5.58
Type
journal article
Language
en
Open access
Licence
cc-by
Locations
  • Journal of Applied Physiology (publishedVersion)
  • PubMed (publishedVersion)
  • Research Bank (Australian Catholic University) (submittedVersion)
  • RMIT Research Repository (RMIT University Library) (submittedVersion)
  • Figshare (submittedVersion, cc-by)
  • Griffith Research Online (submittedVersion)
  • NOVA (University of Newcastle Australia) (submittedVersion)
Funders
Australian Institute of Sport
Topics
  • Life Sciences › Biochemistry, Genetics and Molecular Biology › Cell Biology › Muscle metabolism and nutrition
  • Health Sciences › Medicine › Orthopedics and Sports Medicine › Sports Performance and Training
  • Health Sciences › Medicine › Complementary and alternative medicine › Cardiovascular and exercise physiology
Keywords
carbohydrate availability, carbohydrate restriction, endurance training, substrate oxidation, citrate synthase, mitochondrial enzymes, endurance cycling performance, trained cyclists, triathletes
MeSH terms
Adaptation, Physiological, Adult, Citrate (si)-Synthase, Diet, Dietary Carbohydrates, Energy Metabolism, Exercise Test, Glucose, Glycogen, Humans, Male, Physical Endurance, Exercise, Muscle, Skeletal, Young Adult, Athletes

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