Carb Rinsing: Spitting the Truth
Carbohydrate rinsing is the practice of sipping a fluid, swishing it around the mouth for 5–10 seconds, then spitting the fluid out, rather than ingesting it. During the 2018 World Cup, soccer players from around the world were seen utilizing this practice during warm-ups and half-time. In recent discussions of athletic performance, a controversial issue has been whether carbohydrate rinsing is an effective tool to utilize. On the one hand, some argue that the practice increases endurance capacity and avoids GI distress. On the other hand, it can be argued that carb rinsing may not be superior to ingestion.
When an athlete is performing a moderately-intense exercise for a sustained period of time (>60 min), they need to maintain steady levels of glucose in the bloodstream. Training as a distance runner conditions the body to store carbs as glycogen more efficiently. In the absence of glycogen, the body becomes fatigued.
Distance runners can struggle with digestion problems. During periods of prolonged, intense exercise, the body initiates “flight or fight mode,” and constricts blood vessels to the gastrointestinal system to prioritize blood flow to the muscles. Runners have to find their “fine line” for carb intake during a race. Too much and they can cramp and become nauseous; too little and they become at risk for fatigue.
Carbohydrates rinsing offers a potential benefit for the former group. Not only does the practice decrease the risk of GI distress, but studies shows it may even be a performance enhancer. A recent study showed that carb rinsing in cyclists performing over 2 hours of exercise had faster time trial results than those that were given a placebo treatments. 3
By carb rinsing, the oral receptors in the mouth come into contact with the carb-rich substance. Scientists hypothesize that the contact alone is what causes the brain to stimulate a pleasure and reward response to the body. This concept is similar to how the taste of food can influence a person’s mood.2 The oral contact alone, even without ingestion, can trigger this response. In essence, we are tricking our mind that fuel is coming.
Of course, this cannot be sustained for long periods of time. “Studies have even shown effects of oral carbohydrate mouth rinses compared to placebo with improvements typically between 2% and 3% during exercise lasting approximately 1 h.”4 As with all new practices, it is recommended to try carb-rinsing on training runs and prior to race day. Carb rinsing may benefit distance runners, particularly those who struggle with GI distress.
References
- Carter, J.M., A.E. Jeukendrup, and D.A. Jones (2004b). The effect of carbohydrate mouth rinse on 1-h cycle time trial performance. Med. Sci. Sports Exerc. 36:2107–2111.
- Chambers, E. S., Bridge, M. W., & Jones, D. A. (2009). Carbohydrate sensing in the human mouth: effects on exercise performance and brain activity. The Journal of Physiology, 587(8), 1779–94.
- Jensen, M. P., Klimstra, M. D., Sporer, B., & Stellingwerff, T. (2018). Effect of carbohydrate mouth rinse on performance after prolo
- Jeukendrup AE. Oral carbohydrate rinse: placebo or beneficial? Curr Sports Med Rep. 2013 12(4):222–7
