Performance a matter of taste?

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Adam’s Training Journal

I went for a jog the other day with my friend David. As so often happens, we began chatting about running-geek things.

You see, David is about the best-informed runner I know. In addition to his full-time job, he has taken on the considerable task of knowing absolutely everything there is to know about long-distance running.

For David, no part of the running experience goes unexamined. Is it more efficient to initiate your foot strike with the heel or toe? How many minutes before a race is it optimal to begin a warm-up? To minimize your chances of injury, is it better to run in the morning or evening?

As you’d imagine, in searching out the answers to such questions, David acquires a lot of interesting information. As we clipped along in north Norman on a recent morning, he shared a tidbit that left me scratching my head.

According to David, a recent study found that sports drinks infused with carbohydrates enhanced the performance of endurance athletes. And that they did so even when the athletes did not swallow the drinks. Could this possibly be true?

Dr. Prescott Prescribes

Yes, David is spot-on.

In a study that appeared this spring in the Journal of Physiology, researchers gave one set of endurance athletes a sports drink containing glucose (a sugar) while giving another set of athletes a drink that tasted identical but was flavored with artificial sweeteners. They then asked the athletes to complete a challenging time trial during which they swished with — but didn’t swallow — the two drinks.

The researchers found that the study subjects who rinsed with the sugary drinks outperformed their counterparts who received the artificially sweetened drinks by 2 percent to 3 percent. They also sustained a higher average power output and pulse rate, even though they didn’t perceive that they were working any harder.

Even more confounding, the researchers also tested a third group of athletes by having them swish with a drink laced with a tasteless carbohydrate. This group performed just as well as their counterparts who rinsed with the sugary drinks.

What does it all mean?

When you consume a sports drink during a workout, you’re receiving the obvious benefit of hydration. Your muscles are getting a boost from the easy-to-burn carbohydrates the drinks provide, and you’re restoring electrolytes you lose in perspiration. Still, this study shows there’s even more at work.

It appears that your mouth harbors receptors that respond to carbohydrates (rather than to sweetness). These receptors seem to send signals to areas of the brain associated with reward or pleasure, reducing athletes’ perception of their exertion and, thus, increasing output.

The findings suggest that if you’re looking to optimize performance, traditional sports drinks — as opposed to the newer low- or no-calorie options — are superior. They also suggest that when it comes to the skinny on exercise physiology, you’d do well to listen to your friend David.