Realism in action films
It doesn't exist. Complaining that she couldn't REALLY take all those beatings and still win every fight etc. is just complaining about the nature of action films.
The issue isn't realism. If people object it's not because they don't believe the hero can do these things, it's that they don't WANT to buy into it. They don't like the hero. Seems like a lot of people don't like Carano because she's female - NOT because she's weak or unathletic, but because she's a woman.
When it comes to women punching out men in action movies, I might object too when the woman is someone like Zoe Saldana who's 30 pounds and all skin and bones, because there's clearly no power behind her blows and it looks too fake. But Carano is athletic and her attacks are solid, certainly as much so as those of male action stars.
If we can believe that Bruce Willis can do the things that happen in Die Hard films we can sure as *beep* believe Carano can do what she did in this movie.