Amino acids are the building blocks of protein, and therefore, all of life as we know it. Whether its muscle tissue, hair, skin or nails, it would not exist without amino acids. However, amino acids play other roles in the body, outside of just building tissue. Some carry signals to turn things on or off, whilst others are crucial structural parts of hormones and the like. Four key amino acids that play an important role in sports nutrition (recovery, muscle growth and muscle preservation) are Glutamine and the three Branched Chain Amino Acids (BCAAs – leucine, isoleucine and valine).