Effect of fat adaptation and carbohydrate restoration on metabolism and performance during prolonged cycling

1 Sports Science and Sports Medicine, Australian Institute of Sport, Belconnen 2616; 2 Department of Physiology, The University of Melbourne, Parkville 3052; 3 Exercise Metabolism Group, Department of Human Biology and Movement Science, Royal Melbourne Institute of Technology University, Bundoora 3183; and 4 School of Health Sciences, Deakin University, Burwood 3125, Australia For 5 days, eight well-trained cyclists consumed a random order of a high-carbohydrate (CHO) diet (9.6 g · kg 1 · day 1 CHO, 0.7 g · kg 1 · day 1 fat; HCHO) or an isoenergetic high-fat diet (2.4 g · kg 1 · day 1 CHO, 4 g · kg 1 · day 1 fat; Fat-adapt) while undertaking supervised training. On day 6, subjects ingested high CHO and rested before performance testing on day 7 [2 h cycling at 70% maximal O 2 consumption (SS) + 7 kJ/kg time trial (TT)]. With Fat-adapt, 5 days of high-fat diet reduced respiratory exchange ratio (RER) during cycling at 70% maximal O 2 consumption; this was partially restored by 1 day of high CHO [0.90 ± 0.01 vs. 0.82 ± 0.01 ( P