It seems like every second advert on the TV now is for a sports drink. Sports stars are featured using them, from Brian O’Driscoll to Sean Ó Hailpín and Damien Duff. These drinks make a lot of claims about improving performance and endurance, so how do they work?The essential formula for sports drinks has changed little over the years. They contain sugar for energy, water for hydration, electrolytes such as salt to help with water retention, plus color and flavoring. Formulators play around with the sources and relative concentration of these ingredients to make sure they end up where they’re needed in the body as quickly as possible.