Carb Swishing Improves Performance

Carb Swishing and Spitting

When it comes to nutrition and sports performance, it’s hard to know which source to trust. The vast majority of people don’t have the time to pour over the primary research.  Conclusions are often influenced by marketing. Even if you don’t admit it, marketing techniques drives your decisions.  Companies used what is called marketing science to create a bias. You may have strategies during and post workout that are well intentioned but may be doing nothing.  Or worst yet are counter productive.

This article will examine an instance in which people could be misled by marketing “science”.  This study looks into sports drinks: does an athlete even need to swallow in order to get the benefit.

Carb Swishing, spitting and sensing: Better Than Ingestion?

Maybe you don’t have to choke down all those Gus and Gatorade after all.

“Should I spit or swallow?” is not a question a lot of guys ask themselves very often. According to one study, maybe it should be.

Check out this study called “carbohydrate sensing in the human mouth: effects on exercise performance and brain activity” published in the Journal of Physiology. The researchers explored the relationship of swishing and spitting (rather than drinking) various solutions in your mouth.  What if simply sensing carbohydrate would impact performance? They used a 1 hour cycling trial to test this question.  This is a two part study; only one will be discussed here.

The authors wanted to see, “how rinsing the mouth with a solution containing glucose or maltodextrin, disguised with artificial sweetener, would affect exercise performance.”

Carb Swishing Study design

Eight well trained subjects where given a mystery solution containing either glucose, maltodextrin or placebo disguised by saccharin (sweetener).  They were instructed to swish it around in their mouth, and spit it out at 12.5% completion intervals during a 1 hour max effort cycling trial.

The results showed that although the subjects did not drink the solutions, the carbohydrate solutions outperformed the placebo.  This implies it may not be the actual ingested carbs that benefit the athlete. Rather the perception by the brain of potential carb ingestion. This aligns well with Tim Noake’s central governor theory. He believes that physiology is not the only rate limiter of human performance. More so the brain decides what it feels is safe for the body to do.

This applies to speed and substrate utilization as well as cardiovascular demand. If demand for sugar is getting too high in the periphery, the brain will slow the body down to prevent complete exhaustion of it’s favorite fuel: sugar.  The brain is greedy and high intensity exercise is flat out unnatural.  Many times we have a lot of sugar left in the tank, but the source has been shut down to re-feeding the muscle. When sugar pathways are closed an athlete can’t go as fast.  In some sense, by consuming sugar during a race, you are overriding that.  But sugar ingestion during a race has it’s limitations.

The 1 h cycle trial performances improved by about 2-3 percent in the carbohydrate swishing group.  Maybe it isn’t the “fueling” that matters.  Is it possible that the perception of carbohydrate allows our brain to increase performance?  The subjects reported equal rates of perceived exertion in the various trials.  This means while their actual performance improved and they were doing more work in the carb swishing groups, compared to the placebo group, they felt about the same.  Here are the power output results:





Carb Swishing : what does it all mean?

Two of the big issues people face during performance is gastrointestinal distress (due to the consumption of food during a race) and carrying adequate fuel to last the entire race. Eating during high intensity performance creates an interior competition. Blood is shunted away from the center (digestion) into the periphery during exercise.  Competing with pumping out substrates and digesting food is a common battle we all face on the road.

What if you could put the sugar in your mouth, swish it around, spit it out and get the same response?  Effectively here you are tricking your brain into thinking it’s getting carbs so it doesn’t slow you down to spare them.  Also, you avoid the issues associated with fuel during an exercise bout.  It’s something to consider.

Some studies are a little counter intuitive, but they can provide great examples of how actual science can contradict or call into question marketing “science”.  It may be worthwhile to do a little research.  You may be able to prevent potential fueling drawbacks associated with sugar ingesting during a race.


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