Metabolic, catecholamine, and exercise performance responses to various doses of caffeine

• DOI: 10.1152/jappl.1995.78.3.867
• Publication Date: 2017-12-22T11:28:51Z
• Authors: T. E. Graham; L. L. Spriet
• Keywords: Paraxanthine

This study examined the exercise responses of well-trained endurance athletes to various doses caffeine evaluate impact drug on metabolism and capacity. Subjects (n = 8) withdrew from all dietary sources for 48 h before each four tests. One hour they ingested capsules placebo or (3, 6, 9 mg/kg), rested quietly, then ran at 85% maximal O2 consumption voluntary exhaustion. Blood samples methylxanthine, catecholamine, glucose, lactate, free fatty acid, glycerol analyses were taken every 15 min. Plasma concentration increased with dose (P < 0.05). Its major metabolite, paraxanthine, did not increase between 6 mg/kg doses, suggesting that hepatic was saturated. Endurance enhanced both 3 (increases 22 +/- 7%, respectively; P 0.05) over time 49.4 4.2 min, whereas there no significant effect caffeine. In contrast, plasma epinephrine but greater higher Similarly only highest resulted in increases acids Thus had greatest blood-borne metabolites yet least performance. The lowest little have an ergogenic effect. These results are compatible traditional theory mediates its via catecholamines.