ok. I hope they handle this better. I'm tired of manga thinking just because you have knowledge, your body automatically has the muscle to follow it up. Unless she's secretly training behind people's back, a sickly body should lose stamina quickly and her punches should lack power since she doesn't have the same amount of muscle.
Actually, now that I think about it, she would probably end up with a bunch of sprains and what not from pushing her body too hard.