Energy drinks come in many forms now, and some target athletes.

But do they really help?

CNN reported that a study in the Journal of Psychology found that they really do boost energy output.

In the study, athletes were given drinks that had glucose, a carbohydrate or neither. All of them also contained artificial sweeteners.

The people rinsed their mouths with the drinks while working out and they were tested for endurance.

Those given the drinks with glucose or carbs performed better than the control group by 2 to 3 percent.

MRI scans of their brains showed that both carbs and glucose triggered activity in areas of the brain associated with rewards and pleasure.

The researchers said this shows that just a taste of an energy drink can trick the brain into boosting the body's endurance.

Other recent work has shown that caffeine, which is found in many energy drinks, can help athletes as well.