How much protein? Studies have shown that the optimal protein intake for athletes undergoing high intensity exercise is 1.35g/kg/day which translates into 0.6136 grams/pound/day. Therefore a 200lb athlete would require 122.72 grams of protein.
What these studies also indicate however, is that although protein intakes should be higher than the RDA for strength training athletes, the protein intakes of most strength trained athletes is already at or above this level.
One must remember that protein intake is not the rate limiting factor in muscle mass development.
A diet which provides adequate calories will general provide enough protein as most research studies have indicated.
Thus you definitely don't need 300-600 grams of protein as I've seen some of the muscle mags suggest. And you probably are getting enough protein as it is if you are an athlete.
One possible exception is the athlete who must restrict his/her food intake to lose a great deal of weight in a short time to make a certain weight class. In this case, a small amount of supplemental protein may be warranted.
Remember more is not better when it comes to protein intake. In fact, excessive protein intake over extended periods of time can possibly seriously damage your liver and kidneys.