High5 energy source xtreme drink 14kgenergysource xtreme is a new generation sports drink with a high caffeine content it contains a carbohydrate formulation of maltodextrin and fructose in a ratio of 21 combined with key electrolytes magnesium and caffeine 300mglitre xtreme is intended as a one time caffeine dose athletes use it for caffeine loading prior to or during a major race towards the end of a long ride before or during training for attention and concentration and to increas