Is there a formal statement or opinion in the Catholic Church regarding martial arts?

I have two kids. We don't do contact sports, but some of our friends are involved in American football or hockey, and there's plenty of contact, but it seems like a __game__. Indeed over the course of my life, such sports have tended towards more game less violence through tweaking their rules. Wrestling seems definitively like a contest not based on violence. Boxing I have no defense for, but it's not part of my question. I just witnessed my son's friend's dojo, and the weaponry and actions of the participants sickened me. Now it's possible I'm being a pansy, and the *CCC* allows for self defense, but it sure seemed the participants were leaving communion in their actions. So, is there a formal statement regarding martial arts within Catholicism? Is there a line in which crossed one has sinned?