Energy Source 4:1 is a state of the art sports fuel for use during exercise & to help muscles recover after exercise. Energy Source 4:1 combines a special mix of 4 parts complex carbohydrate to 1 part whey protein. Research shows that this ratio drives more energy into working muscles, providing athletes with a 24% -29% increase in endurance over carbohydrate only drinks & a 57% increase in endurance over water.