title: Effect of caffeine on oxidative stress during maximum incremental exercise.
abstract: Caffeine (1,3,7-trimethylxanthine) is an habitual substance present in a wide variety of beverages and in chocolate-based foods and it is also used as adjuvant in some drugs. The antioxidant ability of caffeine has been reported in contrast with its pro- oxidant effects derived from its action mechanism such as the systemic release of catecholamines. The aim of this work was to evaluate the effect of caffeine on exercise oxidative stress, measuring plasma vitamins A, E, C and malonaldehyde (MDA) as markers of non enzymatic antioxidant status and lipid peroxidation respectively. Twenty young males participated in a double blind (caffeine 5mg·kg- 1 body weight or placebo) cycling test until exhaustion. In the exercise test, where caffeine was ingested prior to the test, exercise time to exhaustion, maximum heart rate, and oxygen uptake significantly increased, whereas respiratory exchange ratio (RER) decreased. Vitamins A and E decreased with exercise and vitamin C and MDA increased after both the caffeine and placebo tests but, regarding these particular variables, there were no significant differences between the two test conditions. The results obtained support the conclusion that this dose of caffeine enhances the ergospirometric response to cycling and has no effect on lipid peroxidation or on the antioxidant vitamins A, E and C. Key PointsCaffeine ingestion may improve maximal aerobic performance in non trained men.Cellular oxidative damage is not altered by caffeine ingestion in maximal aerobic exercises.Antioxidant response to exercise, vitamins A, E and C, is not modified by caffeine action in maximal aerobic efforts.
authors.affiliation: Department of Didactics of Music, Plastic and Corporal Expression, Sport Science Faculty, University of Extremadura , Cáceres, Spain.
authors.forename: Guillermo J
authors.initials: GJ
authors.lastname: Olcina
authors.affiliation: Department of Physiology, Sports Sciences Faculty, University of Extremadura , Cáceres, Spain.
authors.forename: Diego
authors.initials: D
authors.lastname: Muñoz
authors.affiliation: Department of Didactics of Music, Plastic and Corporal Expression, Sport Science Faculty, University of Extremadura , Cáceres, Spain.
authors.forename: Rafael
authors.initials: R
authors.lastname: Timón
authors.affiliation: Department of Pharmacology, Faculty of Medicine, University of Extremadura , Badajoz, Spain.
authors.forename: M Jesús
authors.initials: MJ
authors.lastname: Caballero
authors.affiliation: Department of Analytical Chemistry and Electrochemistry, Sciences Faculty, University de Extremadura . Badajoz, Spain.
authors.forename: Juan I
authors.initials: JI
authors.lastname: Maynar
authors.affiliation: Department of Physiology. School of Physiotherapy. University of Valladolid . Soria, Spain.
authors.forename: Alfredo
authors.initials: A
authors.lastname: Córdova
authors.affiliation: Department of Physiology, Sports Sciences Faculty, University of Extremadura , Cáceres, Spain.
authors.forename: Marcos
authors.initials: M
authors.lastname: Maynar
keywords: Trimethylxanthine; VO2 max; catecholamines; malonaldehyde; vitamins