title: Carbohydrate Dependence During Prolonged, Intense Endurance Exercise.
abstract: A major goal of training to improve the performance of prolonged, continuous, endurance events lasting up to 3 h is to promote a range of physiological and metabolic adaptations that permit an athlete to work at both higher absolute and relative power outputs/speeds and delay the onset of fatigue (i.e., a decline in exercise intensity). To meet these goals, competitive endurance athletes undertake a prodigious volume of training, with a large proportion performed at intensities that are close to or faster than race pace and highly dependent on carbohydrate (CHO)-based fuels to sustain rates of muscle energy production [i.e., match rates of adenosine triphosphate (ATP) hydrolysis with rates of resynthesis]. Consequently, to sustain muscle energy reserves and meet the daily demands of training sessions, competitive athletes freely select CHO-rich diets. Despite renewed interest in high-fat, low-CHO diets for endurance sport, fat-rich diets do not improve training capacity or performance, but directly impair rates of muscle glycogenolysis and energy flux, limiting high-intensity ATP production. When highly trained athletes compete in endurance events lasting up to 3 h, CHO-, not fat-based fuels are the predominant fuel for the working muscles and CHO, not fat, availability becomes rate limiting for performance.
authors.affiliation: The Mary MacKillop Institute for Health Research, Centre for Exercise and Nutrition, Australian Catholic University, Locked Bag 4115, Fitzroy, VIC, 3065, Australia. John.hawley@acu.edu.au.|Research Institute for Sport and Exercise Sciences, Liverpool John Moores University, Liverpool, UK. John.hawley@acu.edu.au.
authors.forename: John A
authors.initials: JA
authors.lastname: Hawley
authors.affiliation: The Mary MacKillop Institute for Health Research, Centre for Exercise and Nutrition, Australian Catholic University, Locked Bag 4115, Fitzroy, VIC, 3065, Australia.
authors.forename: Jill J
authors.initials: JJ
authors.lastname: Leckey
mesh_terms: D000222:Adaptation, Physiological; D003163:Competitive Behavior / Q000502:physiology; D050528:Diet, Carbohydrate-Restricted; D059305:Diet, High-Fat; D004040:Dietary Carbohydrates / Q000008:administration & dosage / Q000378:metabolism*; D004734:Energy Metabolism; D015444:Exercise / Q000502:physiology*; D006801:Humans; D018482:Muscle, Skeletal / Q000378:metabolism; D010084:Oxidation-Reduction; D010806:Physical Education and Training; D010807:Physical Endurance / Q000502:physiology*; D064133:Sports Nutritional Physiological Phenomena
chemical_list: D004040:Dietary Carbohydrates