SSS 2009-04-16（在线收听）

This is Scientific American's 60-Second Science. I'm Cynthia Graber. This will just take a minute.

Hard-training athletes boost their performance with a variety of popular sports drinks. These drinks do work. But not in the way you’d think. That’s according to research just published in The Journal of Physiology.

Researchers tested three drinks. One contained glucose, a sugar. A second had maltodextrin, a tasteless carbohydrate. The third was plain water. All three were laced with artificial sweeteners until they tasted identically sweet.

Endurance athletes rinsed their mouths with one of the three drinks during a tough workout. Surprisingly, athletes that rinsed and spat out the glucose and maltodextrin performed 2 to 3 percent better than those who got the artificial sweetener. They said they didn’t feel like they were working any harder. Then they had their brains scanned by fMRI. The drinks that had real sugar and carbs lit up areas of the brain connected to pleasure and reward. But the fake sweet water did not.

So maybe experiencing pleasure helps override some of the challenge of the workout. And scientists say this means there are receptors in our mouth other than for simple taste, receptors that communicate directly with the brain. Kind of gives new meaning to the term muscle-head.

Thanks for the minute for Scientific American's 60-Second Science. I'm Cynthia Graber.