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

Gregory R. Cox, Sally A. Clark, Amanda J. Cox, Shona L. Halson, Mark Hargreaves, John A. Hawley, Nikki Jeacocke, Rodney J. Snow, Wee Kian Yeo, Louise M. Burke

Research output: Contribution to journalArticleResearchpeer-review

82 Citations (Scopus)

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.

Original languageEnglish
Pages (from-to)126-134
Number of pages9
JournalJournal of Applied Physiology
Volume109
Issue number1
DOIs
Publication statusPublished - 1 Jul 2010
Externally publishedYes

Fingerprint

Carbohydrates
Exercise
Glucose
Citrate (si)-Synthase
Muscles
Water
Quadriceps Muscle
Athletes
Biopsy
Enzymes

Cite this

Cox, Gregory R. ; Clark, Sally A. ; Cox, Amanda J. ; Halson, Shona L. ; Hargreaves, Mark ; Hawley, John A. ; Jeacocke, Nikki ; Snow, Rodney J. ; Yeo, Wee Kian ; Burke, Louise M. / Daily training with high carbohydrate availability increases exogenous carbohydrate oxidation during endurance cycling. In: Journal of Applied Physiology. 2010 ; Vol. 109, No. 1. pp. 126-134.
@article{4f30cb6a80e04819985392e838ffb50c,
title = "Daily training with high carbohydrate availability increases exogenous carbohydrate oxidation during endurance cycling",
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.",
author = "Cox, {Gregory R.} and Clark, {Sally A.} and Cox, {Amanda J.} and Halson, {Shona L.} and Mark Hargreaves and Hawley, {John A.} and Nikki Jeacocke and Snow, {Rodney J.} and Yeo, {Wee Kian} and Burke, {Louise M.}",
year = "2010",
month = "7",
day = "1",
doi = "10.1152/japplphysiol.00950.2009",
language = "English",
volume = "109",
pages = "126--134",
journal = "Journal of Applied Physiology Respiratory Environmental and Exercise Physiology",
issn = "1522-1601",
publisher = "American Physiological Society",
number = "1",

}

Cox, GR, Clark, SA, Cox, AJ, Halson, SL, Hargreaves, M, Hawley, JA, Jeacocke, N, Snow, RJ, Yeo, WK & Burke, LM 2010, 'Daily training with high carbohydrate availability increases exogenous carbohydrate oxidation during endurance cycling' Journal of Applied Physiology, vol. 109, no. 1, pp. 126-134. https://doi.org/10.1152/japplphysiol.00950.2009

Daily training with high carbohydrate availability increases exogenous carbohydrate oxidation during endurance cycling. / Cox, Gregory R.; Clark, Sally A.; Cox, Amanda J.; Halson, Shona L.; Hargreaves, Mark; Hawley, John A.; Jeacocke, Nikki; Snow, Rodney J.; Yeo, Wee Kian; Burke, Louise M.

In: Journal of Applied Physiology, Vol. 109, No. 1, 01.07.2010, p. 126-134.

Research output: Contribution to journalArticleResearchpeer-review

TY - JOUR

T1 - Daily training with high carbohydrate availability increases exogenous carbohydrate oxidation during endurance cycling

AU - Cox, Gregory R.

AU - Clark, Sally A.

AU - Cox, Amanda J.

AU - Halson, Shona L.

AU - Hargreaves, Mark

AU - Hawley, John A.

AU - Jeacocke, Nikki

AU - Snow, Rodney J.

AU - Yeo, Wee Kian

AU - Burke, Louise M.

PY - 2010/7/1

Y1 - 2010/7/1

N2 - 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.

AB - 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.

UR - http://www.scopus.com/inward/record.url?scp=77954332090&partnerID=8YFLogxK

U2 - 10.1152/japplphysiol.00950.2009

DO - 10.1152/japplphysiol.00950.2009

M3 - Article

VL - 109

SP - 126

EP - 134

JO - Journal of Applied Physiology Respiratory Environmental and Exercise Physiology

JF - Journal of Applied Physiology Respiratory Environmental and Exercise Physiology

SN - 1522-1601

IS - 1

ER -