title: Whole-body fat oxidation increases more by prior exercise than overnight fasting in elite endurance athletes.
abstract: The purpose of this study was to compare whole-body fat oxidation kinetics after prior exercise with overnight fasting in elite endurance athletes. Thirteen highly trained athletes (9 men and 4 women; maximal oxygen uptake: 66 ± 1 mL·min(-1)·kg(-1)) performed 3 identical submaximal incremental tests on a cycle ergometer using a cross-over design. A control test (CON) was performed 3 h after a standardized breakfast, a fasting test (FAST) 12 h after a standardized evening meal, and a postexercise test (EXER) after standardized breakfast, endurance exercise, and 2 h fasting recovery. The test consisted of 3 min each at 30%, 40%, 50%, 60%, 70%, and 80% of maximal oxygen uptake and fat oxidation rates were measured through indirect calorimetry. During CON, maximal fat oxidation rate was 0.51 ± 0.04 g·min(-1) compared with 0.69 ± 0.04 g·min(-1) in FAST (P < 0.01), and 0.89 ± 0.05 g·min(-1) in EXER (P < 0.01). Across all intensities, EXER was significantly higher than FAST and FAST was higher than CON (P < 0.01). Blood insulin levels were lower and free fatty acid and cortisol levels were higher at the start of EXER compared with CON and FAST (P < 0.05). Plasma nuclear magnetic resonance-metabolomics showed similar changes in both EXER and FAST, including increased levels of fatty acids and succinate. In conclusion, prior exercise significantly increases whole-body fat oxidation during submaximal exercise compared with overnight fasting. Already high rates of maximal fat oxidation in elite endurance athletes were increased by approximately 75% after prior exercise and fasting recovery.
authors.affiliation: a Department of Food and Nutrition, and Sport Science, University of Gothenburg, PO Box 300, 405 30 Gothenburg, Sweden.|b Department of Public Health, Section for Sport, Arhus University, Dalgas Avenue 4, DK-8000, Aarhus C, Denmark.
authors.forename: Ulrika
authors.initials: U
authors.lastname: Andersson Hall
authors.affiliation: a Department of Food and Nutrition, and Sport Science, University of Gothenburg, PO Box 300, 405 30 Gothenburg, Sweden.
authors.forename: Fredrik
authors.initials: F
authors.lastname: Edin
authors.affiliation: c Swedish NMR Centre, University of Gothenburg, PO Box 465, 405 30, Gothenburg, Sweden.
authors.forename: Anders
authors.initials: A
authors.lastname: Pedersen
authors.affiliation: a Department of Food and Nutrition, and Sport Science, University of Gothenburg, PO Box 300, 405 30 Gothenburg, Sweden.|b Department of Public Health, Section for Sport, Arhus University, Dalgas Avenue 4, DK-8000, Aarhus C, Denmark.
authors.forename: Klavs
authors.initials: K
authors.lastname: Madsen
mesh_terms: D000273:Adipose Tissue / Q000378:metabolism*; D000328:Adult; D056352:Athletes; D001642:Bicycling; D001786:Blood Glucose / Q000378:metabolism; D062408:Breakfast; D002153:Calorimetry, Indirect; D018592:Cross-Over Studies; D015444:Exercise; D005215:Fasting; D005230:Fatty Acids, Nonesterified / Q000097:blood; D005260:Female; D006801:Humans; D006854:Hydrocortisone / Q000097:blood; D007328:Insulin / Q000097:blood; D016014:Linear Models; D050356:Lipid Metabolism; D009682:Magnetic Resonance Spectroscopy; D008297:Male; D055432:Metabolomics; D015999:Multivariate Analysis; D010101:Oxygen Consumption; D010807:Physical Endurance
chemical_list: D001786:Blood Glucose; D005230:Fatty Acids, Nonesterified; D007328:Insulin; D006854:Hydrocortisone
keywords: athlètes d’endurance; capacité d’oxydation des graisses; endurance athletes; exercice préalable; fasting; jeûne; maximal fat oxidation capacity; metabolomics; métabolomique; prior exercise