Proteins are not all created equal. Although most sources of protein in the diet contain all the essential amino acids, they may not be present in adequate amounts to meet the bodies needs. You can look at protein as being either complete or incomplete. A complete protein is said to be a protein that provides all the essential amino acids, in adequate amounts, needed by the body for growth and tissue maintenance. All animal sources of proteins are complete.
Incomplete proteins are proteins that are deficient in one or more of the essential amino acids.
Incomplete proteins inhibit protein synthesis and the remaining amino acids are broken down and wasted as a source of energy. However, they can be combined to form a complete protein to provide sufficient quantities and proportions of all the essential amino acids. When you exercise, and there are vastly different intensities and levels, the protein requirement changes. Let's take a look at the RDA and see what it suggests. Nitrogen balance studies are used to determine amino acid requirements and minimum protein needs.