CHO INGESTION WORKS BEST IN CHO COMPROMISED CONDITIONS BUT DOES NOT PROVIDE A PERFORMANCE ADVANTAGE
Ali, A., Moss, C., Yoo, J. Y., & Breier, B. (2012). Effect of carbohydrate mouth rinse and/or ingestion on high-intensity exercise performance. Presentation 2352 at the 59th Annual Meeting of the American College of Sports Medicine, San Francisco, California; May 29-June 2, 2012.
"There is equivocal data regarding mouth rinsing with carbohydrate (CHO) and exercise performance. It has been suggested that in a fed state, where muscle and liver glycogen stores are not compromised, glucose levels are maintained and hence mouth rinsing will not affect performance."
This study examined the effects of fluid intake, CHO mouth-rinse, and CHO ingestion on cycling performance under glycogen-compromised conditions. Recreationally trained cyclists (N = 9) served as Ss. Four main trials were performed on an electronically-braked cycle ergometer. Trials, separated by seven days, took place over two days. On Day 1 Ss underwent a 90-minute glycogen-reducing exercise protocol, immediately followed by a low-carbohydrate meal and then a subsequent overnight fast. The following morning a one-hour time-trial was attempted. Ss performed a certain amount of work as fast as possible for the performance test. For the main trials Ss did a) mouth rinsed with a 15% CHO solution, b) ingested 7.5% CHO solution, c) mouth rinsed with a taste-matched placebo, or d) ingested taste-matched placebo. Solutions were administered every 12.5% of exercise completed. Blood samples were taken every 25% of exercise.
There were no significant differences in performance time between treatments. However, mean power output was higher in CHO solution condition relative to other trials. There was a main effect of treatment and interaction of treatment x time for plasma glucose. Values were similar at the start of exercise but were higher in the CHO solution condition at 75% and 100% of exercise relative to the other trials. There were treatment and interaction effects for insulin. Levels were higher in the CHO solution condition between 50-100% of exercise relative to other trials.
Implication. Mouth rinsing with a CHO solution in a glycogen-compromised condition did not affect exercise performance. CHO ingestion increased glucose concentrations and improved performance relative to fluid ingestion and CHO mouth rinse trials.
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