Rinsing your mouth with a Carbohydrate Drink Can Shave 1 minute off of a 40km TT. Several studies have been repeatedly indicating just this. Very interesting data.
Research has shown that by simply rinsing your mouth with a carbohydrate solution for 5-10 seconds you can shave off up to 1 minute off of a 40km TT. Similar research has show that carbohydrate mouth rinsing can increase total distance ran over both a 30 and 60 minute run.
A study done by Asker Jeukendrup looked at cyclists performing a 40km TT. In the lab setting, cyclists were asked to rinse their mouths with a non-sweet tasteless maltodextrin solution, containing carbohydrate or a placebo, while performing a 40km TT. The rinsing protocol was standardized so that every 12.5% of the time trial subjects would rinse and spit into a bowl after 5 seconds. Subjects were rested prior to testing for 24hrs and eating a high carbohydrate diet the day before the testing.
The results were significant. Performance was improved with the carbohydrate mouth rinse vs placebo and the results were as effective to similar studies where cyclists ingested the carbohydrates into the body. The 40km TT was completed 1 minute faster without any of the carbohydrate actually entering the body, as carbohydrates are not absorbed in the mouth. So what is going on?
To date the theory is that perhaps there are receptors in the mouth that are sending signals to the brain that food is on the way. Just this signal alone could change the body’s perceived effort making the exercise easier for that time.
Follow up studies were done to take a look at the brain activity using a scan called fMRI. Researchers looked to see if brain activity differed when subjects rinsed with a placebo vs a carbohydrate mouth rinse. Researchers found that with the carbohydrate solution areas of the brain related to reward centers and motor control were activated. This was not the case with the placebo.
During hard exercise the brain receives many signals and over time these signals can begin to be perceived by the brain as unpleasant. Typically this leads to inhibition of motor output often referred to as central fatigue. It seems plausible that signals from the carbohydrate receptors in the mouth are counteracting some of these negative signals. Exactly how this is occurring is unknown but it’s possible that this signal to the brain gives the message that you can relax a bit, energy is on the way. Clearly there is communication between the mouth and the brain occurring even before carbohydrates enter the body. This could give good reason to just suck on candies for the same effect, however that has not been studied to date….I hope to see this soon! Maybe Jolly Ranchers will make a comeback? 🙂
Researchers have also looked at whether the mouth brain relationship was related to “sweetness.” Researchers used an artificial sweetener in the same mouth rinsing protocol and found that the same areas of the mouth were not stimulated as they were with the tasteless non sweet maltodextrin. This would again indicate that there are carbohydrate receptors in the mouth, however that they are separate from sweetness receptors.
To date there are no known carbohydrate receptors in the human mouth that have been identified. This definitely will create more research into this area.
In practice it appears that simply rinsing your mouth during exercise lasting 30minutes to 1 hour can have significant performance outcomes. Ingesting the carbohydrate solution drink had the same outcomes so there is no disadvantage to drinking the drink during exercise besides the calories ingested.
Other studies have been done which have shown no significant difference with carbohydrate mouth rinsing. At this point there seems to be more research required into why some subjects are seeing significant improvements and others are not, when using similar nutrition controls and testing methods.
For now, if the possibility of a significant improvement exists perhaps it’s worth bringing a bottle on that 40km TT after all?
Carter JM, Jeukendrup AE, Jones DA: The effect of carbohydrate mouth rinse on 1-h cycle time trial performance. Med Sci Sports Exerc 2004, 36:2107-11.
Pottier A, Bouckaert J, Gilis W, Roels T, Derave W: Mouth rinse but not ingestion of a carbohydrate solution improves 1-h cycle time trial performance. Scand J Med Sci Sports 2010, 20:105-111.
Carter JM, Jeukendrup AE, Jones DA: The effect of carbohydrate mouth rinse on 1-h cycle time trial performance. Med Sci Sports Exerc 2004, 36:2107-11