If you just want good credit for an EC that requires dedication, listing on the application will do that. If you want the coach begging the admissions committee to admit you, you might want to contact the coach first and not just hope that they figure out that you are a good addition. I have more experience in college recruting, but I think it will work similarly. The coach only gets pull on a certain number of apps. You want to make sure that you are one of them.