I don't have cites at hand, but I recall reading about a few studies where performance in a hard cycling test was increased by drinking sugar water. The interesting thing was that it still worked if you spit the water back out after swishing it around in your mouth. The idea behind this is that the body "holds back" some reserve energy stores by feeling fatigue before energy supplies are actually exhausted, and that consuming calories while exercising can induce your nervous system to push a little harder before the onset of fatigue signals.

I've definitely felt a difference in my own climbing sessions when I started drinking a sports drink instead of water. It could be a placebo effect, of course.

Have you heard of this research? If so, any opinion?