Journal Article10.1152/AJPENDO.1997.273.2.E268
Fatty acid oxidation is directly regulated by carbohydrate metabolism during exercise.
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TL;DR: Sub substrate oxidation during exercise can be regulated by increased glycolytic flux that is accompanied by a direct inhibition of long-chain fatty acid oxidation, as indicated by a coordination of effects on adipose tissue and muscle.
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Abstract: We determined whether increased glycolytic flux from hyperglycemia and hyperinsulinemia directly reduces fatty acid oxidation during exercise. Fatty acid oxidation rates were measured during constant-rate intravenous infusion of trace amounts of a long-chain fatty acid ([1-13C]palmitate; Pal) vs. a medium-chain fatty acid ([1-13C]octanoate; Oct). Six endurance-trained men cycled for 40 min at 50% of maximal O2 uptake 1) after an overnight fast (“fasting”) and 2) after ingestion of 1.4 g/kg of glucose at 60 min and again 10 min before exercise (Glc). Glc caused hyperinsulinemia, a preexercise blood glucose of 6 mM, and a 34% reduction in total fat oxidation during exercise due to an approximately equal reduction in oxidation of plasma-free fatty acids (FFA) and intramuscular triglycerides (all P < 0.05). Oxidation of Pal was significantly reduced during Glc compared with fast (i.e., 70.0 +/- 4.1 vs. 86.0 +/- 1.9% of tracer infusion rate; P < 0.05). However, Glc had no effect on Oct oxidation, which is apparently not limited by mitochondrial transport. Furthermore, Glc reduced plasma FFA appearance 36% (P < 0.05), indicating a coordination of effects on adipose tissue and muscle. In summary, substrate oxidation during exercise can be regulated by increased glycolytic flux that is accompanied by a direct inhibition of long-chain fatty acid oxidation. These observations indicate that carbohydrate availability can directly regulate fat oxidation during exercise.
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Citations
Enhanced Endurance Performance by Periodization of Carbohydrate Intake: "Sleep Low" Strategy.
Laurie-Anne Marquet,Jeanick Brisswalter,Julien Louis,Eve Tiollier,Louise M. Burke,John A. Hawley,Christophe Hausswirth +6 more
TL;DR: In this article, the authors investigated the effect of a chronic dietary periodization strategy on endurance performance in trained athletes and found that short-term periodization of dietary CHO availability around selected training sessions promoted significant improvements in submaximal cycling economy, as well as supra-maximal cycle capacity and 10 km running time in trained endurance athletes.
Influence of high-carbohydrate mixed meals with different glycemic indexes on substrate utilization during subsequent exercise in women
TL;DR: Altering the GI of the carbohydrate within a meal significantly changes the postprandial hyperglycemic and hyperinsulinemic responses in women.
124
Regulatory mechanisms in the interaction between carbohydrate and lipid oxidation during exercise
TL;DR: This review summarizes the work describing the interaction between CHO and fat metabolism in human skeletal muscle during exercise and presents the theories that may account for CHO/fat interaction during exercise.
117
Caffeine increases exogenous carbohydrate oxidation during exercise
TL;DR: Compared with glucose alone, 5 mg x kg(-1) x h (-1) of caffeine coingested with glucose increases exogenous CHO oxidation, possibly as a result of an enhanced intestinal absorption.
117
Carbohydrate supplementation during prolonged cycling exercise spares muscle glycogen but does not affect intramyocellular lipid use.
Trent Stellingwerff,Hanneke Boon,Annemie P. Gijsen,Jos H. C. H. Stegen,Harm Kuipers,Luc J. C. van Loon +5 more
TL;DR: It is concluded that carbohydrate supplementation during prolonged cycling exercise does not modulate IMTG use but spares muscle glycogen use during the initial stages of exercise in endurance-trained men.
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