title: Oral Presence of Carbohydrate and Caffeine in Chewing Gum: Independent and Combined Effects on Endurance Cycling Performance.
abstract: The oral presence of carbohydrate (CHO) and caffeine (CAF) may independently enhance exercise performance, but their influence on performance during prolonged exercise is less known.
  
  
  OBJECTIVE
  To determine the independent and combined effects of CHO and CAF administered in chewing gum during a cycling time trial (TT) after prolonged exercise.
  
  
  METHODS
  Eleven male cyclists (32.2 ± 7.5 y, 74.3 ± 6.8 kg, 60.2 ± 4.0 mL · kg-1 · min-1 VO2peak) performed 4 experimental trials consisting of 90-min constant-load cycling at 80% of their second ventilatory threshold (207 ± 30 W), followed immediately by a 20-km TT. Under double-blinded conditions, cyclists received placebo (PLA), CHO, CAF, or a combined CHO+CAF chewing gum at 0-, 5-, 10-, and 15-km points of the TT.
  
  
  RESULTS
  Overall TT performance was similar across experimental and PLA trials (%mean difference ± 90%CL 0.2% ± 2.0%, 0.4% ± 2.2%, 0.1% ± 1.8% for CHO, CAF, and CHO+CAF). Compared with PLA, mean power output tended to be higher in the first 2 quarters of the TT with CHO (1.6% ± 3.1% and 0.8% ± 2.0%) and was substantially improved in the last 2 quarters during CAF and CHO+CAF trials (4.2% ± 3.0% and 2.0% ± 1.8%). There were no differences in average heart rate (ES <0.2) and only small changes in blood glucose (ES 0.2), which were unrelated to performance. Blood lactate was substantially higher post-TT for CAF and CHO+CAF (ES >0.6).
  
  
  CONCLUSIONS
  After prolonged constant-load cycling, the oral presence of CHO and CAF in chewing gum, independently or in combination, did not improve overall performance but did influence pacing.
authors.affiliation: High Performance Sport New Zealand, Auckland, New Zealand.
authors.forename: Katherine T
authors.initials: KT
authors.lastname: Oberlin-Brown
authors.forename: Rodney
authors.initials: R
authors.lastname: Siegel
authors.forename: Andrew E
authors.initials: AE
authors.lastname: Kilding
authors.forename: Paul B
authors.initials: PB
authors.lastname: Laursen
mesh_terms: D000328:Adult; D054874:Athletic Performance / Q000502:physiology*; D001642:Bicycling / Q000502:physiology*; D001786:Blood Glucose; D002110:Caffeine / Q000008:administration & dosage*; D002638:Chewing Gum; D018592:Cross-Over Studies; D004040:Dietary Carbohydrates / Q000008:administration & dosage*; D004311:Double-Blind Method; D006339:Heart Rate; D006801:Humans; D019344:Lactic Acid / Q000097:blood; D008297:Male; D010807:Physical Endurance / Q000187:drug effects*
chemical_list: D001786:Blood Glucose; D002638:Chewing Gum; D004040:Dietary Carbohydrates; D019344:Lactic Acid; D002110:Caffeine