I guess it's her passion (cheerleading). Let her go for it if she likes it! I don't believe in stopping anyone from his or her passion, unless it's illegal lol.

Actually if you hit me on the back with a ball during a physical education lesson, chances are I'd not even turn around to see who hit me with it unless it was really hard, in which case I think I'd find it hard to smile. (I didn't notice it wasn't very hard lol)