*queue Shaneequa "OH NO YOU DIDN'T*
Firefighting is quite literally a single standard job if there ever was one, and my station in Alaska had 3 women assigned to it.
They could denver drill my ass out a window without a hitch and I'm 6'3 and about 330 with all my gear on.
Our initial training is specifically designed to demonstrate all the worst case scenarios of weight, exertion, and uncomfortable circumstances specifically to cull the herd of applicants.... and this was for a paid-on-call "Volunteer" department. 2 females in the class. One broke (again, 2nd shot at the basic indoc) and one passed. I would venture that pass rate was about 70% for the men, either failures to train/adapt or LOM'ed. Truth be told, it's pretty hard to FAIL regardless. There are techniques to get over/around/through the size/weight difference that WORK for firefighting. The other fact is that in firefighting you work as a team. I know that I can swing the TNT tool hard, and if another member on the crew can't get the gap, then I'm gonna put my weight into it and help. I also know that same 120 lb female that might just not be able to gap that door CAN handle a 2 1/2 line on her own, because she's DONE it right there with me.
Biggest thing, just like Ranger school... the standard must not change, period. The standard for my station was that for specific circumstances that involved firefighter rescue (below grade, denver drill, etc) they had to rescue ME because I was the biggest firefighter at the station. Worst case scenario is what we always trained for.
If you can't do it due to size/sex, figure out how to.
Can't figure out how to?
Go do EMS. LOL