Simplified, protein is what the body’s structure is made of. Bones, muscles, hair, organs, immune cells and many hormones are all proteins.
For a muscle to get stronger, it must add protein to its existing mass. When muscles work hard, they build up lactic acid. Muscle cells have enzymes to breakdown lactic acid and these enzymes are also proteins.
Proteins are chains made up of amino acids. These are linked together (like beads on a string) to form proteins, which differ based on which aminos are used and in what order. For instance, a hair protein has a different string of aminos than a muscle protein.
There are 22 known amino acids, but our bodies only need 8 of them to construct all of its proteins. These are called “essential amino acids” because we cannot live without them; they must be part of our dietary intake.
After a hard workout, muscle cells need to rebuild their proteins. If the aminos they need are unavailable to the cell at that time, those proteins will not be built. And the whole sequence of repair will be incomplete or delayed. As a result, new muscle growth won’t happen or happens belatedly, so the training effect one expects does not happen, and even worse, you breakdown and get inured.
The same thing happens with many proteins that our immune system is made of. After a hard workout or competition, if there isn’t enough protein intake to complete the repair process and keep your immune system proteins at the optimum level, you can get sick. Bottom line: we need the proteins that will give us the correct proportions of the eight essential amino acids, in a form that the body can use easily, without excess nitrogen waste.