We've all been conditioned into thinking that it's perfectly healthy to drink this type of crap; it's far more difficult for a company to make money from water than from a colorful sweet tasting drink. Unfortunately we are not designed to drink sugary drinks, until recent times our sugar would be been slowly released from food in the stomach e.g. a piece of fruit, meaning we had a slow steady release of sugar into our blood stream. Now instead we down a sugary drink which then floods our blood stream with sugar. We are not designed for this. If we do this long term we're far more likely to end up obese and/or diabetic.
If you want to take something to help you exercise/compete then go for Beetroot
http://news.bbc.co.uk/1/hi/8186947.stm