Pre.Fuel is a scientifically engineered combination of branched chain amino acids (BCAAs), an amino blend, essential vitamins, minerals and caffeine. This unique blend has been specially formulated by our leading sports specialists and manufactured from high quality ingredients to create an expert pre.workout supplement. Pre.Fuel is a scientifically engineered combination of branched chain amino acids (BCAAs), an amino blend, essential vitamins, minerals and caffeine. This unique blend has been specially formulated by our leading sports specialists and manufactured from high quality ingredients to create an expert pre.workout supplement.