title: Caffeine Affects Time to Exhaustion and Substrate Oxidation during Cycling at Maximal Lactate Steady State.
abstract: This study analyzed the effects of caffeine intake on whole-body substrate metabolism and exercise tolerance during cycling by using a more individualized intensity for merging the subjects into homogeneous metabolic responses (the workload associated with the maximal lactate steady state-MLSS). MLSS was firstly determined in eight active males (25 ± 4 years, 176 ± 7 cm, 77 ± 11 kg) using from two to four constant-load tests of 30 min. On two following occasions, participants performed a test until exhaustion at the MLSS workload 1 h after taking either 6 mg/kg of body mass of caffeine or placebo (dextrose), in a randomized, double-blinded manner. Respiratory exchange ratio was calculated from gas exchange measurements. There was an improvement of 22.7% in time to exhaustion at MLSS workload following caffeine ingestion (95% confidence limits of ±10.3%, p = 0.002), which was accompanied by decrease in respiratory exchange ratio (p = 0.001). These results reinforce findings indicating that sparing of the endogenous carbohydrate stores could be one of the several physiological effects of caffeine during submaximal performance around 1 h.
authors.affiliation: Santa Catarina State University, Human Performance Research Group, Rua Pascoal Simone, 358, Coqueiros, Florianópolis, Santa Catarina 88080-350, Brazil. cruz.rso@gmail.com.
authors.forename: Rogério Santos de Oliveira
authors.initials: RS
authors.lastname: Cruz
authors.affiliation: Santa Catarina State University, Human Performance Research Group, Rua Pascoal Simone, 358, Coqueiros, Florianópolis, Santa Catarina 88080-350, Brazil. deaguiar.rafael@hotmail.com.
authors.forename: Rafael Alves
authors.initials: RA
authors.lastname: de Aguiar
authors.affiliation: Santa Catarina State University, Human Performance Research Group, Rua Pascoal Simone, 358, Coqueiros, Florianópolis, Santa Catarina 88080-350, Brazil. tiagoturnes89@gmail.com.
authors.forename: Tiago
authors.initials: T
authors.lastname: Turnes
authors.affiliation: Federal University of Santa Catarina, Physical Effort Laboratory, Pantanal, Florianópolis, Santa Catarina 88040-900, Brazil. luizguilherme@cds.ufsc.br.
authors.forename: Luiz Guilherme Antonacci
authors.initials: LG
authors.lastname: Guglielmo
authors.affiliation: Abt. Medizin, Training und Gesundheit, Inst. Sportwissenschaft und Motologie, Philipps Universität Marburg, Marburg 35037, Germany. ralph.beneke@staff.uni-marburg.de.
authors.forename: Ralph
authors.initials: R
authors.lastname: Beneke
authors.affiliation: Santa Catarina State University, Human Performance Research Group, Rua Pascoal Simone, 358, Coqueiros, Florianópolis, Santa Catarina 88080-350, Brazil. fabrizio.caputo@udesc.br.
authors.forename: Fabrizio
authors.initials: F
authors.lastname: Caputo
mesh_terms: D000328:Adult; D001642:Bicycling / Q000502:physiology*; D002110:Caffeine / Q000008:administration & dosage / Q000378:metabolism / Q000494:pharmacology*; D000697:Central Nervous System Stimulants / Q000008:administration & dosage / Q000378:metabolism / Q000494:pharmacology*; D004311:Double-Blind Method; D004734:Energy Metabolism; D015444:Exercise / Q000502:physiology; D005080:Exercise Test; D017079:Exercise Tolerance / Q000187:drug effects* / Q000502:physiology; D005221:Fatigue / Q000378:metabolism*; D006801:Humans; D019344:Lactic Acid / Q000097:blood*; D008297:Male; D010084:Oxidation-Reduction / Q000187:drug effects; D011659:Pulmonary Gas Exchange; D013997:Time Factors; D055815:Young Adult
chemical_list: D000697:Central Nervous System Stimulants; D019344:Lactic Acid; D002110:Caffeine
keywords: endurance; fat metabolism; muscle glycogen; submaximal performance