title: Improved cycling time-trial performance after ingestion of a caffeine energy drink.
abstract: BACKGROUND
  Not all athletic competitions lend themselves to supplementation during the actual event, underscoring the importance of preexercise supplementation to extend endurance and improve exercise performance. Energy drinks are composed of ingredients that have been found to increase endurance and improve physical performance.
  
  
  OBJECTIVE
  The purpose of the study was to investigate the effects of a commercially available energy drink, ingested before exercise, on endurance performance.
  
  
  METHODS
  The study was a double-blind, randomized, crossover design. After a 12-hr fast, 6 male and 6 female trained cyclists (mean age 27.3 +/- 1.7 yr, mass 68.9 +/- 3.2 kg, and VO2 54.9 +/- 2.3 ml x kg-1 x min-1) consumed 500 ml of either flavored placebo or Red Bull Energy Drink (ED; 2.0 g taurine, 1.2 g glucuronolactone, 160 mg caffeine, 54 g carbohydrate, 40 mg niacin, 10 mg pantothenic acid, 10 mg vitamin B6, and 10 microg vitamin B12) 40 min before a simulated cycling time trial. Performance was measured as time to complete a standardized amount of work equal to 1 hr of cycling at 70% Wmax.
  
  
  RESULTS
  Performance improved with ED compared with placebo (3,690 +/- 64 s vs. 3,874 +/- 93 s, p < .01), but there was no difference in rating of perceived exertion between treatments. b-Endorphin levels increased during exercise, with the increase for ED approaching significance over placebo (p = .10). Substrate utilization, as measured by open-circuit spirometry, did not differ between treatments.
  
  
  CONCLUSIONS
  These results demonstrate that consuming a commercially available ED before exercise can improve endurance performance and that this improvement might be in part the result of increased effort without a concomitant increase in perceived exertion.
authors.affiliation: Department of Kinesiology and Health Education, University of Texas, Austin, TX 78712-0360, USA.
authors.forename: John L
authors.initials: JL
authors.lastname: Ivy
authors.forename: Lynne
authors.initials: L
authors.lastname: Kammer
authors.forename: Zhenping
authors.initials: Z
authors.lastname: Ding
authors.forename: Bei
authors.initials: B
authors.lastname: Wang
authors.forename: Jeffrey R
authors.initials: JR
authors.lastname: Bernard
authors.forename: Yi-Hung
authors.initials: YH
authors.lastname: Liao
authors.forename: Jungyun
authors.initials: J
authors.lastname: Hwang
mesh_terms: D000328:Adult; D019540:Area Under Curve; D001481:Basal Metabolism / Q000187:drug effects / Q000502:physiology; D001628:Beverages; D001642:Bicycling / Q000502:physiology*; D001786:Blood Glucose / Q000378:metabolism; D002110:Caffeine / Q000008:administration & dosage*; D018592:Cross-Over Studies; D004311:Double-Blind Method; D005260:Female; D006801:Humans; D007773:Lactates / Q000378:metabolism; D008297:Male; D010101:Oxygen Consumption / Q000187:drug effects* / Q000502:physiology; D010807:Physical Endurance / Q000187:drug effects* / Q000502:physiology; D013647:Task Performance and Analysis
chemical_list: D001786:Blood Glucose; D007773:Lactates; D002110:Caffeine