title: Enhancement of 2000-m rowing performance after caffeine ingestion.
abstract: OBJECTIVE
  To investigate the effect of caffeine ingestion on short-term endurance performance in competitive rowers.
  
  
  METHODS
  In this randomized double-blind crossover study, eight competitive oarsmen (peak oxygen uptake [VO2peak] 4.7+/-0.4 L x min(-1), mean +/- SD) performed three familiarization trials of a 2000-m rowing test on an air-braked ergometer, followed by three experimental trials at 3- to 7-d intervals, each 1 h after ingesting caffeine (6 or 9 mg x kg(-1) body mass) or placebo. Trials were preceded by a standardized warm-up (6 min at 225+/-39 W; 75+/-7.7% VO2peak).
  
  
  RESULTS
  Urinary caffeine concentration was similar before ingestion (approximately 1 mg x L(-1)) but rose to 6.2+/-3.6 and 14.5+/-7.0 mg x L(-1) for the low and high caffeine doses, respectively. Plasma free fatty acid concentration before exercise was higher after caffeine ingestion (0.29+/-0.17 and 0.39+/-0.20 mM for 6 and 9 mg x kg(-1), respectively) than after placebo (0.13+/-0.05 mM). Respiratory exchange ratio during the warm-up was also substantially lower with caffeine (0.94+/-0.09 and 0.93+/-0.06 for the low and high dose) than with placebo (0.98+/-0.12). Subjects could not distinguish between treatments before or after the exercise test. Both doses of caffeine had a similar ergogenic effect relative to placebo: performance time decreased by a mean of 1.2% (95% likely range 0.4-1.9%); the corresponding increase in mean power was 2.7% (0.4-5.0%). Performance time showed some evidence of individual differences in the effect of caffeine (SD 0.9%; 95% likely range 1.5 to -0.9%).
  
  
  CONCLUSIONS
  Ingestion of 6 or 9 mg x kg(-1) of caffeine produces a worthwhile enhancement of short-term endurance performance in a controlled laboratory setting.
authors.affiliation: Department of Human Biology and Movement Science, RMIT University, Bundoora, Victoria Australia.
authors.forename: C R
authors.initials: CR
authors.lastname: Bruce
authors.forename: M E
authors.initials: ME
authors.lastname: Anderson
authors.forename: S F
authors.initials: SF
authors.lastname: Fraser
authors.forename: N K
authors.initials: NK
authors.lastname: Stepto
authors.forename: R
authors.initials: R
authors.lastname: Klein
authors.forename: W G
authors.initials: WG
authors.lastname: Hopkins
authors.forename: J A
authors.initials: JA
authors.lastname: Hawley
mesh_terms: D002110:Caffeine / Q000494:pharmacology* / Q000652:urine; D018592:Cross-Over Studies; D004311:Double-Blind Method; D016552:Ergometry; D005230:Fatty Acids, Nonesterified / Q000097:blood; D006801:Humans; D008297:Male; D010807:Physical Endurance / Q000187:drug effects; D013177:Sports / Q000502:physiology*
chemical_list: D005230:Fatty Acids, Nonesterified; D002110:Caffeine