It has long been established that carbohydrates around training or competition improve performance but researchers from the University of Birmingham, UK wanted to see if the underlying mechanism for this is metabolic or central nervous system mediated. In order to investigate this, the researchers employed simple carbohydrate mouth rinsing, where participants gargled a carbohydrate drink but did not swallow, a bit like using mouthwash. This practice had a positive effect on performance regardless of the taste of the drink. While they did not identify oral receptors, the researchers speculate that there must be some in existence that are hard-wired to the brain, almost like they are giving the brain an advanced message that fuel is en route. Some smaller sugars are able to enter the bloodstream sublingually through the membrane inside of the mouth which may be a possibility of the location of these receptors. No doubt future research will be into finding their whereabouts.
As for application, I would figure this probably has more relevance for performance athletes and those who want to improve performance without having to fill their stomachs will a lot of liquid. Distance runners come to mind. As for bodybuilders, I’d suggest just drinking the carbs and getting the full benefit of the calories. Unless you are dieting and having a poor workout and want to kick it up a notch without taking in many calories.
Jeukendrup AE, Chambers ES. Oral carbohydrate sensing and exercise performance. Curr Opin Clin Nutr Metab Care. 2010 May 5.