Anabolic / AntiCatabolic BioEfficient Protein Amino acids are the building blocks for muscle tissue. In order to achieve maximum muscle growth you must have an adequate supply of amino acids to feed you muscles. Certain amino acids are more important than others for stimulating and supporting muscle growth. These amino acids are called the Critical Five amino acids which include glutamine arginine and BCAAs Leucine isoleucine and valine. ProbolicSRs engineered protein matrix of whey concentrate soy isolate and casein is precisely formulated to supply the absolute highest levels of these Critical Five amino acids.