Your coach is right. Indeed, diversified protein is the best choice, but only if you choose high-quality protein with PDCAAS score of 1.0, and you must choose protein with different amino acid release times, such as "whey protein, milk casein, soy protein isolate, Whey Protein Isolation" and so on. . Protein is composed of many kinds of amino acids, and each protein has its own advantages, so combining them is the best choice.

This has been tested and proved by foreign sports organizations many years ago, so don't be too superstitious about WPC80 pure whey protein, and don't underestimate casein and soy protein isolate in milk. There is not much difference in the effect of muscle training. You can build muscles after training. It is suggested to choose protein products developed by professional sports nutrition companies. I feel that the nitrogen protein powder mentioned by your coach is ok, and it is definitely much better than pure whey protein.