Abstract des Autors

Purpose: High intensity exercise and carbohydrate intake seem to inhibit fat oxidation. The aim of the present study was to investigate how much fat metabolism is influenced by carbohydrate intake before and during prolonged exercise at the intensity of the absolutely highest fat oxidation. Methods: 14 endurance trained male athletes (VO2peak 58.3 ± 6.7 ml/kg/min) were studied over 120 min at 75% VO2peak on a cycling ergometer with and without carbohydrate intake. Energy expenditure, oxidation rates of carbohydrates and fat were calculated and lactate concentrations were measured. Results: Intake of 120 g carbohydrates 90 min before exercise and 20 g every 20 minutes during exercise compared with the same exercise without carbohydrate intake have no influence on total energy expenditure (2158 ± 112 kcal vs. 2165 ± 385 kcal). Carbohydrate oxidation was significantly lower without carbohydrate intake (482 ± 90 g/2h vs. 437 ± 119 g/2h). Concentration of lactate was significantly lower during exercise with carbohydrate intake. Conclusion: Intake of carbohydrates before (120 g 90 min before exercise) and during exercise (20 g/20min) during cycling of 120 minutes at 75% VO2peak corresponding to the intensity of the highest fat oxidation rate results in an equal energy expenditure during exercise with and increased carbohydrate oxidation and suppressed fat oxidation compared with the same trial without intake of carbohydrates. Concentration of lactate was significantly lower during exercise with carbohydrate intake which can not properly be explained. Verf.-Referat