Metabolic and performance responses during endurance exercise after high-fat and high-carbohydrate meals

Oxford Lipid Metabolism Group, Radcliffe Infirmary, Oxford OX2 6HE; University Department of Anaesthesia, University Hospitals of South Manchester, Withington Hospital, Manchester M20 2LR; and Centre for Sport and Exercise Science, Liverpool John Moores University, Liverpool L3 3AF, United Kingdom We studied the effects of preexercise meal composition on metabolic and performance-related variables during endurance exercise. Eight well-trained cyclists (maximal oxygen uptake 65.0 to 83.5 ml · kg 1 · min 1 ) were studied on three occasions after an overnight fast. They were given isoenergetic meals containing carbohydrate (CHO), protein (P), and fat (F) in the following amounts (g/70 kg body wt): high-carbohydrate meal, 215 CHO, 26 P, 3 F; high-fat meal, 50 CHO, 14 P, 80 F. On the third occasion subjects were studied after an overnight fast. Four hours after consumption of the meal, subjects started exercise for 90 min at 70% of their maximal oxygen uptake, followed by a 10-km time trial. The high-carbohydrate meal compared with the high-fat meal resulted in significant decreases ( P