title: No effect of carbohydrate feeding on 16 km cycling time trial performance.
abstract: The aim of this study is to investigate the effects of CHO ingestion during high intensity exercise performance lasting approximately 25 min. Twelve endurance trained male cyclists (age 19-41 years; body mass 73.2 +/- 4.2 kg; VO(2)max 66.4 +/- 6.2 ml kg(-1) min(-1)) completed a simulated 16 km time trial (457 +/- 37 kJ) time trial in the lab on three occasions. Once they received a 6% carbohydrate electrolyte solution (CHO) and twice they received the same electrolyte containing placebo drink (PLA). Carbohydrate or placebo drinks were ingested 5 min before the start (4 ml kg(-1)) and at 25, 50, and 75% of completion of the time trial (1.4 ml kg(-1)). The CHO drink was a 6% sucrose-glucose-electrolyte solution. No differences were observed in the time to complete the time trials with either treatment. Time in min:s were 25:30 +/- 1:34 and 25:27 +/- 1:46 for the two placebo trials and 25:38 +/- 1:59 in the CHO trial. Power output during the time trials was also remarkably similar: 300 +/- 37 W, 301 +/- 39 W and 299 +/- 40 W, respectively. Pacing strategies and heart rate were identical in all three trials. From the two placebo trials, a coefficient of variation for this performance task was calculated to be 1.1%. Data from this study provides evidence that carbohydrate ingestion during short high intensity exercise (approximately 30 min, 85-90% VO(2)max) does not improve performance. Furthermore, this study found a very low coefficient of variation (1.1%) for a simulated 16 km time trial.
authors.affiliation: School of Sport and Exercise Sciences, University of Birmingham, Edgbaston, Birmingham B15 2TT, UK. A.E.Jeukendrup@bham.ac.uk
authors.forename: Asker E
authors.initials: AE
authors.lastname: Jeukendrup
authors.forename: Shaun
authors.initials: S
authors.lastname: Hopkins
authors.forename: Luis Fernando
authors.initials: LF
authors.lastname: Aragón-Vargas
authors.forename: Carl
authors.initials: C
authors.lastname: Hulston
mesh_terms: D000328:Adult; D001628:Beverages; D001642:Bicycling; D018592:Cross-Over Studies; D004040:Dietary Carbohydrates / Q000008:administration & dosage*; D004311:Double-Blind Method; D006339:Heart Rate; D006801:Humans; D008297:Male; D053580:Muscle Strength; D010101:Oxygen Consumption; D010807:Physical Endurance; D013647:Task Performance and Analysis; D013997:Time Factors; D055815:Young Adult
chemical_list: D004040:Dietary Carbohydrates