basicly any sport is gonna mess u up, not in a big way but like running, it jams ur shin into ur knees, so after awhile it will start to get painful. And u will get bulky muscles, in ballet u pull up ur body and elongate ur muscles, in every other sport u dont train for that. So ur best bet is to not do sports. i know it sux cuz i also want to be a pro. dancer more over a prima tho, and im a big tomboy so i love to get out there with the guys and play sports and get dirty but now that im on pointe and advancing, i cant do that anymore, in fact my knees are already kinda weird and have to take car of them.
so i hope i helped....hope ur dreams come true!!!!!!!!