The Influence of Low Versus High Carbohydrate Diet on a 45-min Strenuous Cycling Exercise

Stavros A. Kavouras, John P. Troup, Jacqueline R. Berning

Research output: Contribution to journalArticle

15 Scopus citations

Abstract

To examine the effects of a 3-day high carbohydrate (H-CHO) and low carbohydrate (L-CHO) diet on 45 min of cycling exercise, 12 endurance-trained cyclists performed a 45-min cycling exercise at 82 ± 2% VO 2peak following an overnight fast, after a 6-day diet and exercise control. The 7-day protocol was repeated under 2 randomly assigned dietary trials H-CHO and L-CHO. On days 1-3, subjects consumed a mixed diet for both trials and for days 4-6 consumed isocaloric diets that contained either 600 g or 100 g of carbohydrates, for the H-CHO and the L-CHO trials, respectively. Muscle biopsy samples, taken from the vastus lateralis prior to the beginning of the 45-min cycling test, indicated that muscle glycogen levels were significantly higher (p <.05) for the H-CHO trial (104.5 ± 9.4 mmol/ kg wet wt) when compared to the L-CHO trial (72.2 ± 5.6 mmol/kg wet wt). Heart rate, ratings of perceived exertion, oxygen uptake, and respiratory quotient during exercise were not significantly different between the 2 trials. Serum glucose during exercise for the H-CHO trial significantly increased (p <.05) from 4.5 ± 0.1 mmol·L-1 (pre) to 6.7 ± 0.6 mmol·L-1 (post), while no changes were found for the L-CHO trial. In addition, post-exercise serum glucose was significantly greater (p <.05) for the H-CHO trial when compared to the L-CHO trial (H-CHO, 6.7 ± 0.6 mmol·L-1;L-CHO, 5.2 ± 0.2 mmol·L-1). No significant changes were observed in serum free fatty acid, triglycerides, or insulin concentration in either trial. The findings suggest that L-CHO had no major effect on 45-min cycling exercise that was not observed with H-CHO when the total energy intake was adequate.

Original languageEnglish (US)
Pages (from-to)62-72
Number of pages11
JournalInternational Journal of Sport Nutrition and Exercise Metabolism
Volume14
Issue number1
DOIs
StatePublished - Feb 2004
Externally publishedYes

Keywords

  • Carbo-loading
  • FFA
  • Glucose
  • High fat diet
  • Muscle glycogen

ASJC Scopus subject areas

  • Medicine (miscellaneous)
  • Orthopedics and Sports Medicine
  • Nutrition and Dietetics

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