Karate? I've done some when I was about 10-12 years old. Not much. I reached, like, orange belt, and in the only two duel thingies we did, all I did was dodge, because both hitting and blocking seemed painful. Super warrior, rwar.
Though if it's related to seiza, nope. We sat indian-style. I just sit this way because it's comfy and allows me to warm my legs while sitting, too.