title: Effect of high-fat, high-carbohydrate, and high-protein meals on metabolism and performance during endurance cycling.
abstract: 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.
authors.affiliation: Department of Exercise Science in the Institute of Food, Nutrition, and Human Health and Massey University, Private Bag 756, Wellington, New Zealand.
authors.forename: David S
authors.initials: DS
authors.lastname: Rowlands
authors.forename: Will G
authors.initials: WG
authors.lastname: Hopkins
mesh_terms: D000328:Adult; D001642:Bicycling / Q000502:physiology*; D001786:Blood Glucose / Q000378:metabolism; D018592:Cross-Over Studies; D004040:Dietary Carbohydrates / Q000008:administration & dosage* / Q000378:metabolism; D004041:Dietary Fats / Q000008:administration & dosage* / Q000378:metabolism; D004044:Dietary Proteins / Q000008:administration & dosage* / Q000378:metabolism; D004311:Double-Blind Method; D004734:Energy Metabolism / Q000502:physiology*; D005080:Exercise Test; D005230:Fatty Acids, Nonesterified / Q000097:blood; D005934:Glucagon / Q000378:metabolism; D005990:Glycerol / Q000378:metabolism; D006801:Humans; D007328:Insulin / Q000378:metabolism; D008297:Male; D010084:Oxidation-Reduction; D010807:Physical Endurance / Q000502:physiology*; D005082:Physical Exertion / Q000502:physiology
chemical_list: D001786:Blood Glucose; D004040:Dietary Carbohydrates; D004041:Dietary Fats; D004044:Dietary Proteins; D005230:Fatty Acids, Nonesterified; D007328:Insulin; D005934:Glucagon; D005990:Glycerol