I believe that if males and females played competitive or professional sport together there would be many things that could and would go wrong. First off, when it comes to contact sports there would be countless amounts of complaints and backlash of a male injured or generally hurt a female player. Given the fact that naturally women have a slightly weaker bone structure and form and male athletes are at the height of their health and fitness the women could get injured quite bad and many "old-fashioned" people would make claims of violence against women and whatnot. It's not intentional or sexist it's just part of the game and due to this male players would usually need to restrain themselves when confronting a female player because of the damage they could cause. It's also a natural and unavoidable situation to have men and women disagreeing. They will always argue about something because in the end they aren't the same kind of people and they will have different needs and opinions on how the sports should be played.
but girls know the risk but it seems so sexist that myself as a girl cant play with the boys even though i know and so do they that i can play the big league just like them girls should play with boys full stop !!