Carbohydrate enhances running performance by increasing the availability of “premium” glucose fuel in the working muscles. Right? Maybe not.
A series of studies performed by a team of scientists at the University of Birmingham, England, has shown that endurance performance is increased when athletes merely swish a sports drink around in their mouths and spit it out periodically during exercise. The reason is that the carbs activate carbohydrate receptors in the brain that communicate with a part of the brain that regulates perceived exertion. The result is a decrease in perceived exertion that boosts performance.
It’s unlikely that a carbohydrate mouth rinse can fully match all of the benefits of actually swallowing a sports drink. For example, swallowing a sports drink rehydrates as well as supplies energy. But in running, where it is difficult to drink a lot, swishing and spitting a sports drink may be a good complement to ingesting it.