You can analyse the issue of are these women masculine or not to death when you're just looking at images and videos, especiallly as the photo shoots show them all hard and pumped up.
But when you meet them and look them in the eye, they're just women and that's the first and most overriding thing you notice about them.
Sure some of them are very strong women, who can lift you, squeeze you and pin you, but you're not internally debating their level of masculinity while it's happening, unlike when you look at their photos.
As for the bodybuilders whom you think are super feminine with their lovely hair and make up and insta****-filtered skin, you know, the ones you contrast favourably with the "manly" ones ...
Well I'm afraid they're nowhere near as feminine as you think, and you ought to see them coming out of the gym in their sweats with no makeup.
If you had a cartoon image of Barbie with biceps, their beefiness will probably strike you as unexpectedly masculine in person.
The fact is, feminine is a loaded term implying a certain look and gender role and (lack of) physical capability.
No big ffb really fits that mould, but that doesn't make them manly either, and you're never going to mistake them for a man in person.
That said, there is a bit of gender swapping going on when you have a private encounter with a more muscular woman who can put her strong arms around you and pick you up, but that's part of the thrill.