Is it strange that i am aroused by my girlfriend's physical superiorit

My girlfriend is a very ladylike southern girl, but when it comes to any physical challenges, she is my superior. She is a faster runner, a better swimmer and, as I have found in our 'burglar' games a superior boxer.
Three times we have played a game where I am the burglar and she must defend herelf. In wrestling alone I can pin her, but in a fist fight she is faster and I haven't been able to land a punch. She just demolishes me.
The follow up sex is the best, as her confidence leads to some very domineering sex.