To test this hypothesis, Carter and colleagues investigated the impact of a carbohydrate mouth-rinse solution on 1-h time trial performance. The use of a mouth-rinse treatment, in which a CHO solution is spat out without swallowing, was chosen to remove any influence of the gut or exogenous CHO oxidation on performance. Participants were reported to cycle faster after a mouth rinse with a 6.4% maltodextrin solution at every 12.5% of the trial completed compared with a placebo rinse. The authors concluded that CHO mouth rinsing improves time trial performance and that the mechanism responsible might be an increase in central drive or motivation mediated by glucose receptors in the mouth. However in the former study, subjects were tested in a fasted state, which is impractical compared to how athletes normally prepare for training and competition.