title: Physiological and cognitive responses to caffeine during repeated, high-intensity exercise.
abstract: This study investigated the effects of caffeine on repeated, anaerobic exercise using a double-blind, randomized, crossover design. Seventeen subjects (five female) underwent cognitive (reaction time, number recall) and blood (glucose, potassium, catecholamines, lactate) testing before and after consuming caffeine (6 mg/kg), placebo, or nothing (control). An exercise test (two 60 s maximal cycling bouts) was conducted 90 min after caffeine/placebo consumption. Plasma caffeine concentrations significantly increased after caffeine ingestion, however, there were no positive effects on cognitive or blood parameters except a significant decrease in plasma potassium concentrations at rest. Potentially negative effects of caffeine included significantly higher blood lactate compared to control and significantly slower time to peak power in exercise bout 2 compared to control and placebo. Caffeine had no significant effect on peak power, work output, RPE, or peak heart rate. In conclusion, caffeine had no ergogenic effect on repeated, maximal cycling bouts and may be detrimental to anaerobic performance.
authors.affiliation: Institute of Sport and Exercise Science, James Cook University, Townsville, Queensland 4811, Australia.
authors.forename: Melissa J
authors.initials: MJ
authors.lastname: Crowe
authors.forename: Anthony S
authors.initials: AS
authors.lastname: Leicht
authors.forename: Warwick L
authors.initials: WL
authors.lastname: Spinks
mesh_terms: D000328:Adult; D001786:Blood Glucose / Q000378:metabolism; D002110:Caffeine / Q000097:blood* / Q000494:pharmacology*; D002395:Catecholamines / Q000097:blood; D000697:Central Nervous System Stimulants / Q000097:blood / Q000494:pharmacology*; D003071:Cognition / Q000187:drug effects* / Q000502:physiology*; D018592:Cross-Over Studies; D004311:Double-Blind Method; D015444:Exercise / Q000502:physiology*; D005080:Exercise Test; D005260:Female; D006801:Humans; D019344:Lactic Acid / Q000097:blood; D008297:Male; D010101:Oxygen Consumption / Q000187:drug effects / Q000502:physiology; D011188:Potassium / Q000097:blood
chemical_list: D001786:Blood Glucose; D002395:Catecholamines; D000697:Central Nervous System Stimulants; D019344:Lactic Acid; D002110:Caffeine; D011188:Potassium