Effect of high-fat, high-carbohydrate, and high-protein meals on metabolism and performance during endurance cycling

The effect of pre-exercise meal composition on metabolism and performance in cycling were investigated in a crossover study. Twelve competitive cyclists ingested high-fat, high-carbohydrate, or high-protein meals 90 min before a weekly exercise test. The test consisted of a 1-hour pre-load at 55% pe...

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Bibliographic Details
Published in:International journal of sport nutrition 2002-09, Vol.12 (3), p.318-335
Main Authors: Rowlands, David S, Hopkins, Will G
Format: Article
Language:English
Subjects:
Adult
Bicycling - physiology
Blood Glucose - metabolism
Cross-Over Studies
Dietary Carbohydrates - administration & dosage
Dietary Carbohydrates - metabolism
Dietary Fats - administration & dosage
Dietary Fats - metabolism
Dietary Proteins - administration & dosage
Dietary Proteins - metabolism
Double-Blind Method
Energy Metabolism - physiology
Exercise Test
Fatty Acids, Nonesterified - blood
Glucagon - metabolism
Glycerol - metabolism
Humans
Insulin - metabolism
Male
Oxidation-Reduction
Physical Endurance - physiology
Physical Exertion - physiology
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Summary:The effect of pre-exercise meal composition on metabolism and performance in cycling were investigated in a crossover study. Twelve competitive cyclists ingested high-fat, high-carbohydrate, or high-protein meals 90 min before a weekly exercise test. The test consisted of a 1-hour pre-load at 55% peak power, five 10-min incremental loads from 55 to 82% peak power (to measure the peak fat-oxidation rate), and a 50-km time trial that included three 1-km and 4-km sprints. A carbohydrate supplement was ingested throughout the exercise. Relative to the high-protein and high-fat meals, the high-carbohydrate meal halved the peak fat-oxidation rate and reduced the fat oxidation across all workloads by a factor of 0.20 to 0.58 (p =.002-.0001). Reduced fat availability may have accounted for this reduction, as indicated by lower plasma fatty acid, lower glycerol, and higher pre-exercise insulin concentrations relative to the other meals (p =.04-.0001). In contrast, fat oxidation following the high-protein meal was similar to that following the high-fat meal. This similarity was linked to evidence suggesting greater lipolysis and plasma fat availability following high-protein relative to high-carbohydrate meals. Despite these substantial effects on metabolism, meal composition had no clear effect on sprint or 50-km performance.
ISSN:1526-484X
1050-1606
1543-2742
DOI:10.1123/ijsnem.12.3.318