It sounds bizarre, but several studies have shown that rinsing sugary water around your mouth before exercising can have a noticeable effect on your performance. The practice is known as “carbohydrate mouth rinse”, or more commonly just “carb rinsing”.
A 2017 study from the European Journal of Sport Science found that a group of men in their early 20s were able to do more bench presses & squats and could do a faster 10 metre sprint after rinsing their mouths with a sugary mixture.
In a different study, researcher Trent Stellingwerff from the Canadian Sport Institute in Vancouver found that carb-rinsing significantly increased peak power when volunteers were given a series of leg exercises. “We were really shocked. The rinse has an instantaneous effect. It allows subjects to perceive that the task is easier.”
We were really shocked. The rinse has an instantaneous effect. It allows subjects to perceive that the task is easier.
Of course, consuming carbohydrates supplies the body with energy which is essential for performing strenuous tasks, but taking in too much right before exercise can lead to discomfort and bowel issues. So what is the benefit of simply tasting carbs before spitting it out? Scientists aren’t entirely sure yet, but the going theory is that the body is tricked into thinking you are eating or drinking something sweet, which means a dose of energy must be on its way. As a result, the body allows you to go all-out and push yourself.
Neil Clarke, a sports and exercise scientist at Coventry University, puts it this way: “When you carb-rinse, it activates the reward and arousal areas of the brain. The brain expects a carbohydrate boost, so it gets aroused. You’re almost tricking the brain. The brain says: ‘OK, carbs are on the way, we can push harder now.'”
The brain expects a carbohydrate boost, so it gets aroused. You’re almost tricking the brain.
Could this be a simple placebo effect? Apparently not – other studies have ruled this out by giving athletes maltodextrin – a carbohydrate that has no taste – without telling them what they were being given. These subjects still showed a boost in performance.
Clarke thinks that carb-rinsing can improve performance by around 2-3%. This may not sound like much, but margins like this would represent a huge advantage at elite level.