title: Effects of fat adaptation on glucose kinetics and substrate oxidation during low-intensity exercise.
abstract: This study was designed to determine the effects of fat adaptation on carbohydrate and fat oxidation in conditioned horses during low-intensity exercise. Five mature Arabians were studied. The study was conducted as a crossover design with 2 dietary periods, each of 10 week's duration: a) a control (CON) diet, and b) a fat-supplemented (FAT) diet. The total amount of digestible energy (DE) supplied by the fat in the CON and FAT diets was 7% and 29%, respectively. During each period, the horses completed exercise tests at the beginning of the period (Week 0) and after 5 and 10 weeks on the diet. Tests consisted of 90 min of exercise at a speed calculated to elicit 35% VO2max on a treadmill inclined to 3 degrees. Oxygen consumption (VO2), carbon dioxide production (VCO2), and respiratory exchange ratio (RER) were measured at 15-min intervals. For determination of glucose kinetics, a stable isotope ([6-6-d2] glucose) technique was used. Compared to the CON diet, FAT diet consumption for 5-10 weeks was associated with an altered metabolic response to low-intensity exercise, as evidenced by a more than 30% reduction in the production and utilisation of glucose; a decrease in RER; a decrease in the estimated rate of whole-body carbohydrate utilisation; and an increase in the whole-body rate of lipid oxidation during exercise.
authors.affiliation: Kentucky Equine Research, Versailles 40383, USA.
authors.forename: J D
authors.initials: JD
authors.lastname: Pagan
authors.forename: R J
authors.initials: RJ
authors.lastname: Geor
authors.forename: P A
authors.initials: PA
authors.lastname: Harris
authors.forename: K
authors.initials: K
authors.lastname: Hoekstra
authors.forename: S
authors.initials: S
authors.lastname: Gardner
authors.forename: C
authors.initials: C
authors.lastname: Hudson
authors.forename: A
authors.initials: A
authors.lastname: Prince
mesh_terms: D000222:Adaptation, Physiological; D000818:Animals; D001786:Blood Glucose / Q000032:analysis; D002245:Carbon Dioxide / Q000378:metabolism; D018592:Cross-Over Studies; D004040:Dietary Carbohydrates / Q000378:metabolism*; D004041:Dietary Fats / Q000378:metabolism*; D005080:Exercise Test / Q000662:veterinary; D005947:Glucose / Q000493:pharmacokinetics*; D006003:Glycogen / Q000032:analysis; D006736:Horses / Q000378:metabolism*; D008297:Male; D018482:Muscle, Skeletal / Q000378:metabolism; D010084:Oxidation-Reduction; D010101:Oxygen Consumption / Q000502:physiology*; D010805:Physical Conditioning, Animal / Q000502:physiology*; D011659:Pulmonary Gas Exchange / Q000502:physiology; D011897:Random Allocation
chemical_list: D001786:Blood Glucose; D004040:Dietary Carbohydrates; D004041:Dietary Fats; D002245:Carbon Dioxide; D006003:Glycogen; D005947:Glucose