No effect of carbohydrate feeding on 16 km cycling time trial performance
Jeukendrup, Asker E.
Aragón Vargas, Luis Fernando
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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; VO2max 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 (*30 min, 85–90% VO2max) does not improve performance. Furthermore, this study found a very low coefficient of variation (1.1%) for a simulated 16 km time trial.
External link to the item10.1007/s00421-008-0838-z
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