If you've attended a 5k, 10k or any other kind of road race lately, you've no doubt seen the athletes with GU Energy Gel in their hands or going into their mouths. Racer's everywhere swear by GU, a concentrated energy fuel designed with the endurance athlete in mind.What's in GU Energy Gel? GU's ingredients fall into 3 categories. For energy, you a get a blend of simple and complex carbs, plus a shot of caffeine and electrolytes to max out energy production at the cellular level. For endurance, GU gives you complex carbs from maltodextrin plus mineral citrates (potassium citrate, sodium citrate and citric acid) to help reduce acid build-up in muscles. Branched chain amino acids (BCAAs) serve as a vital fuel source during extreme exertion; they also aid in recovery . Histidine, an essential amino acid, acts as a carnosine precursor that also helps neutralize lactic acid build-up in muscles. Finally, for recovery, GU Energy Gel contains the antioxidant vitamins C & E to protect defend muscles from exercise-induced free radicals. Ginger provides additional antioxidant protection while soothing the stomach. Sea salt helps replace vital sodium and trace minerals.