title: Effect of increased fat availability on metabolism and exercise capacity.
abstract: Several procedures have been utilized to elevate plasma free fatty acid (FFA) concentration and increase fatty acid (FA) delivery to skeletal muscle during exercise. These include fasting, caffeine ingestion, L-carnitine supplementation, ingestion of medium-chain and long-chain triglyceride (LCT) solutions, and intravenous infusion of intralipid emulsions. Studies in which both untrained and well-trained subjects have ingested LCT solutions or received an infusion of intralipid (in combination with an injection of heparin) before exercise have reported significant reductions in whole-body carbohydrate oxidation and decreased muscle glycogen utilization during both moderate and intense dynamic exercise lasting 15-60 min. The effects of increased FA provision on rates of muscle glucose uptake during exercise are, however, equivocal. Despite substantial muscle glycogen sparing (15-48% compared with control), exercise capacity is not systematically improved in the face of increased FA availability.
authors.affiliation: Exercise Metabolism Group, School of Medical Sciences, RMIT University, PO Box 71, Bundoora, Victoria 3083, Australia. john.hawley@rmit.edu.au
authors.forename: John A
authors.initials: JA
authors.lastname: Hawley
mesh_terms: D002110:Caffeine / Q000008:administration & dosage; D002331:Carnitine / Q000008:administration & dosage; D002149:Energy Intake; D015444:Exercise / Q000502:physiology; D017079:Exercise Tolerance / Q000502:physiology*; D005217:Fat Emulsions, Intravenous / Q000008:administration & dosage; D005227:Fatty Acids / Q000378:metabolism*; D006801:Humans; D018482:Muscle, Skeletal / Q000378:metabolism*; D013177:Sports / Q000502:physiology; D014280:Triglycerides / Q000008:administration & dosage
chemical_list: D005217:Fat Emulsions, Intravenous; D005227:Fatty Acids; D014280:Triglycerides; D002110:Caffeine; D002331:Carnitine