The short answer is, you need all the amino acids in the
proper proportions to build muscle optimally.
Building muscle is a complex process.
To simplify this answer, I will speak in generalities.
In order to build muscle you first need to have provided sufficient intensity of stimuli from training.
Assuming you train with appropriate progressions and intensity...
You need to rest adequately to allow muscle to hypertrophy (grow.)
The next thing is diet!
You must eat a balanced meal (for hormonal balance and nutrient supply) frequently enough to insure that your body never has to go into a state where it needs nutrients and you have not supplied them. This would be about every 3 to 3-1/2 hours.
When possible, the majority of these meals should be composed of a lean complete protein, a whole food starchy carbohydrate, and a fibrous carbohydrate (vegetable or sometimes a fruit).
Eating this way would ideally supply the full compliment of amino acids every 3 to 3-1/2 hours.
In building muscle, there is what we will call the limiting factor to growth.
If you take in a certain amount of amino acids (protein) from a food source that is incomplete (does not have all the necessary amino acids) then the ability of your body to build muscle is limited to the available amino acids - up to the limit of the most limiting amino acid.
The body has stores and can produce certain amino acids, termed non-essential amino acids, and it is often said that one only needs to supply the essential amino acids for growth. This is directed at the normal population and NOT at bodybuilders and athletes. The demands for growth require that all the necessary building blocks be present at the time of growth or growth is limited.
For optimal muscle gains, you will want to assure that your diet is sufficient to meet the demands of ongoing growth!
There are plenty of technical details I have left out, but I hope this answered your question in a useful way!
<message edited by danmirage on Sunday, January 21, 2007 2:48 PM>