Whenever you do any physical activity your body produces sweat. This is simply its way of keeping everything at the right temperature. The Premier League players and professionals you see flying around pitches have to have enough liquid in their bodies before a game to cope with the fluid they will lose as they sweat. They drink before a game, at half-time and when the game has finished. This should be the same for anyone who plays football. The correct term is 'Hydration'.
PA ImagesIf you're one of the best players in the world, it makes sense to be able to perform. Lionel Messi is a dribbling genius, but his sprints and skills would be limited if he didn't hydrate properly.