In 2005 researchers at Maastricht University in the Netherlands compared the effects of water and a sports drink in runners. Ninety-eight runners were asked to complete an 18 km time trial on three separate occasions, drinking water on one occasion and a couple of different sports drink formulations in the other two trials. Severe gastrointestinal complaints were relatively uncommon, but they occurred more frequently with both sports drinks than they did with water. These findings confirm anecdotal reports that some runners are unable to tolerate any amount of carbohydrate intake during running and must therefore completely forgo the benefits of consuming carbs during races.
Or must they? In a series of clever studies, Asker Jeukendrup and colleagues at the University of Birmingham, England, found that runners and cyclists were able to complete time trials faster when they periodically rinsed their mouths with a sports drink and spit it out. Although the sports drink was never swallowed and the carbs in it never reached the athletes’ muscles, where they could actually be used to supply energy, those carbs stimulated carbohydrate receptors on the tongue of the athletes, and these receptors in turn delivered signals to a part of the brain that is involved in regulating perceived effort during exercise. Activation of this “reward center” in the brain caused running and cycling to feel easier, enabling the athletes to sustain a faster pace in time trials without exceeding their maximum pain tolerance.
This discovery raises the possibility that runners with sensitive stomachs can enjoy at least some of the benefit of using a sports drink without actually drinking it. If you are unable to ingest any carbohydrate during races without risking severe GI distress, then your optimal race nutrition plan entails drinking water by thirst and rinsing out your mouth with a sports drink. I know it sounds weird, but if you’re not using any other source of carbs, tasting and spitting out the event’s official sports drink will very likely enable you to finish faster than if you drink only water.
Most aid stations in marathons and half marathons are divided into two sections. Water is offered in the first section and sports drink in the second. If you have made a commitment to execute Race Nutrition Plan #4 in a race, take a cup of water from the first section of each aid station and drink as little or as much of it as your thirst requires and your stomach comfort permits. Then take a cup of sports drink from the second section and rinse your mouth with it, spitting it out instead of swallowing. By merely tasting carbs frequently throughout the race you may get almost as much benefit as you would get from ingesting carbs without putting your stomach under duress.