Its a misconception that if athletes go vegan or follow a vegetarian diet they will lose on muscles. I have worked with wrestler Sushil Kumar for his 2 Olympic Medals and he is pure vegetarian but still a very powerful athlete.
Athletes lose muscles because:
Getting essential required nutrients on a vegan diet require an expert planning. If you have that covered there is nothing you should as an athlete be worry about.
Ryan Fernando is an Award-winning celebrity Sports Nutritionist with 2GUINNESS world record and 2 Olympic medals under his belt. His client list include Olympic wrestler Sushil Kumar, cricketer Shikhar Dhawan & bollywood superstars Aamir Khan & Abhishek Bachchan. He is Chief Nutritionist at QUA Nutrition Signature Clinics.