( Dear student the question was updated because you were originally asking two questions in one. Muscle mass and athletic performance are two separate questions).
Proteins are the muscles building blocks and for athletes wanting to grow their muscles, it is recommended that they eat at least a gram of protein per body weight. However for those who want to increase their muscle mass they will actually have to eat a larger quantity. Calculations and recommendations ranger from 1.5 to 2 times body weight in grams. So for a 180 pound individual wanting to increase their muscle mass, the recommended daily protein intake would be 360 grams. Getting this kind of calories from protein based foods (mostly meats) would require a significant amount of servings. This is where protein powder supplements come in, they contain significant amount of protein per gram of serving. This allows the athlete to get the required amount of protein without consuming too much food in a single serving. On the flip side if they are already getting their target protein intake from solid food alone, then there may be no need for protein powder supplementation.