title: The effects of different doses of caffeine on endurance cycling time trial performance.
abstract: This study investigated the effects of two different doses of caffeine on endurance cycle time trial performance in male athletes. Using a randomised, placebo-controlled, double-blind crossover study design, sixteen well-trained and familiarised male cyclists (Mean ± s: Age = 32.6 ± 8.3 years; Body mass = 78.5 ± 6.0 kg; Height = 180.9 ± 5.5 cm VO2(peak) = 60.4 ± 4.1 ml x kg(-1) x min(-1)) completed three experimental trials, following training and dietary standardisation. Participants ingested either a placebo, or 3 or 6 mg x kg(-1) body mass of caffeine 90 min prior to completing a set amount of work equivalent to 75% of peak sustainable power output for 60 min. Exercise performance was significantly (P < 0.05) improved with both caffeine treatments as compared to placebo (4.2% with 3 mg x kg(-1) body mass and 2.9% with 6 mg x kg(-1) body mass). The difference between the two caffeine doses was not statistically significant (P = 0.24). Caffeine ingestion at either dose resulted in significantly higher heart rate values than the placebo conditions (P < 0.05), but no statistically significant treatment effects in ratings of perceived exertion (RPE) were observed (P = 0.39). A caffeine dose of 3 mg x kg(-1) body mass appears to improve cycling performance in well-trained and familiarised athletes. Doubling the dose to 6 mg x kg(-1) body mass does not confer any additional improvements in performance.
authors.affiliation: School of Public Health, Research Centre for Clinical and Community Practice Innovation, Griffith Health Institute, Griffith University, Queensland, Australia. b.desbrow@griffith.edu.au
authors.forename: Ben
authors.initials: B
authors.lastname: Desbrow
authors.forename: Caren
authors.initials: C
authors.lastname: Biddulph
authors.forename: Brooke
authors.initials: B
authors.lastname: Devlin
authors.forename: Gary D
authors.initials: GD
authors.lastname: Grant
authors.forename: Shailendra
authors.initials: S
authors.lastname: Anoopkumar-Dukie
authors.forename: Michael D
authors.initials: MD
authors.lastname: Leveritt
mesh_terms: D000328:Adult; D054874:Athletic Performance / Q000502:physiology*; D001642:Bicycling / Q000502:physiology*; D001827:Body Height; D001835:Body Weight; D002110:Caffeine / Q000008:administration & dosage / Q000494:pharmacology*; D000697:Central Nervous System Stimulants / Q000008:administration & dosage / Q000494:pharmacology*; D018592:Cross-Over Studies; D004311:Double-Blind Method; D015444:Exercise / Q000502:physiology*; D006339:Heart Rate / Q000187:drug effects; D006801:Humans; D008297:Male; D053580:Muscle Strength; D010101:Oxygen Consumption / Q000187:drug effects; D010465:Perception; D010807:Physical Endurance / Q000187:drug effects* / Q000502:physiology; D005082:Physical Exertion; D010936:Plant Extracts / Q000008:administration & dosage / Q000494:pharmacology*; D014937:Work; D055815:Young Adult
chemical_list: D000697:Central Nervous System Stimulants; D010936:Plant Extracts; D002110:Caffeine