If you’ve watched enough major marathons, you may have noticed a seeming oddity: Some elites grab their fluid bottles at the 40K mark, even though they’re going to finish only six or seven minutes later. What’s the point?
Look carefully, and you’ll see that in many cases the runners appear to take a drink and spit it out. This practice is purposeful—over the last decade there’s been increasing evidence that rinsing your mouth with a carbohydrate drink but not swallowing it can help you run faster. To date, most of the research on the topic has lacked a crucial real-world element, in that the athletes swishing and spitting were doing so after not having carbohydrates before or during exercise.
So kudos to the Canadian researchers whose new study shows that rinsing with a sports drink boosts performance even if you haven’t been denying yourself carbs. In the study, published in Medicine & Science in Sports & Exercise, cyclists who rode at a steady effort for two hours before doing a 30-minute time trial performed almost 2 percent better on the time trial when they rinsed with a carb drink. According to the researchers, the trick can help not just at the end of long races but also during shorter workouts.
First, a brief explainer: How does rinsing with a carbohydrate drink improve performance, given that you don’t ingest the carbohydrates that would theoretically fuel your working muscles?
“Food is known to simulate mood and perception, and carbohydrate is a major food that has a great impact on mood/perception,” Matt Jensen, from the University of Victoria and the lead researcher on the new study, wrote in an email. “So even without ingesting carbohydrate, our body is already at work responding to the idea that carbohydrate is about to enter the system. This has been backed up by looking at brain stimulation differences between carbohydrate and artificial sweeteners. You would think that since the artificial sweeteners are very sweet that the body would react to it, but that is not the case. The body only reacts to true carbohydrate.”
As leading sport nutritionist Asker Jeukendrup has noted, many of us have experienced this phenomenon. If you feel dizzy and weak after a long run and then eat or drink something sugary, you’ll feel better almost immediately “This means that there must be connections from the mouth directly to the brain,” Jeukendrup writes. Jensen says these connections, signaling that carbs are on the way, “then trick the body into doing more, because the brain is always trying to limit damage, and if it thinks carbohydrate is limited, it will reduce muscle activation, etc.”
Again, though, most previous research on the practice introduced an artificial condition of not allowing carbs before and during the rinse-and-spit hard effort. In that situation, it makes sense that your brain would be looking for any sign it can get that carbs are on the way. But that’s not how most people go about something like a half marathon or marathon. Instead, you probably eat a light breakfast a few hours before the race and you take in carbs, via drinks and/or gels, during the race.
In the new study, the cyclists did the 2.5-hour ride (two hours at steady effort, then the time trial) on two occasions. Both times, they ate a snack two hours before the ride, and took in 30 grams of carbohydrate during the first two hours of the ride. (Thirty grams of carbohydrate provides 120 calories, which is a little more than the amount provided by many energy gels or 12 to 20 ounces of store-bought carbohydrate drink.) During the time trials, the cyclists rinsed several times for five to 10 seconds with a carbohydrate drink or a placebo that tasted the same. When they rinsed with carbs, they performed 1.7 percent better, with almost all of the improvement coming in the final minutes.
So, when does it make sense to rinse with sport drink instead of swallowing it? This brings us back to elite runners grabbing their fluid bottles with just more than a mile to go in a marathon. Rinsing at this point delivers the promise of carbs even when there’s not time for the body to process them.
Drinking in the last 20 to 40 minutes of a race might not make sense because of the time needed to absorb and transport the carbs to working muscles, Jensen says. If the new study’s finding of a 1.7 percent performance boost at the end of a long effort doesn’t sound significant, consider that’s the difference between a 3:56 marathon and a 4:00 marathon.
More broadly, rinsing is a good option when your stomach might not be able to handle drinking. That extends rinsing’s potential uses to not only the last several miles of a long run or race, but even to speed workouts, because other studies have found brief boosts in power output after rinsing. Give rinsing and spitting a try. What do you have to lose except a little sports drink?