People mislabel themselves on any dating app that allows a "body type" entry. You'll find that a very wide range of people consider themselves "Fit/Athletic". Played softball one year in 2nd grade? "Athletic". Went to the gym three days in a row back in 2015? "Fit". Dating apps are a waste, in general, but especially for this niche. Gatsby's suggestion is your best bet.
...of course you'll also have to contain yourself and be cool when meeting in person. That means don't call them by name before they've told you their name and don't walk up grabbing at their biceps! Restraint
In 6 years of swiping left I have seen maybe 8 girls over 4 apps that look like they’re really into fitness. I really don’t think it’s the way to go. Just go to a gym
It's much better to start working out and maybe try and volunteer at local shows in order to network.
This is why I don't understand people who post questions like this. We all know that fit women are in the minority in most countries (speaking from being in the United States, where we have an obesity epidemic,) and among fit women actual muscular women are even more rare. What you see on dating sites is merely a reflection of the demographics associated with wherever you are based out of.
And another thing to realize: fit women are in heavy demand, and that includes muscular women. Yes, men who are attracted to muscular women versus more "conventional" types are in the minority, but there are more men who are into buff women than you might realize. In another forum years ago, I was asking a similar question about how to find and date female bodybuilders, and saying that it shouldn't be that hard because not many guys like female bodybuilders. An actual female bodybuilder responded to me saying that there are actually a LOT of guys who like buff women, and that she had no shortage of male attention (she even posted a screenshot of her inbox!)
Muscular women don't need "fit dating sites" because sports like bodybuilding, powerlifting, crossfit and olympic lifting have a male majority in the environments that these women spend a lot of time in (I know that there are women who are gay or bisexual, but for the purposes of this post I am assuming heterosexual). It is basically like being a man in a dance studio or in a book club. It's not going to be hard to find someone who is into the same thing they are into, and since strength sports (or really any kind of athletic discipline) is a lifestyle commitment, they're going to want to find someone who lives a similar lifestyle. As someone who lifts regularly and eats clean, I would not want to date someone who is sedentary and constantly eats junk food, even when factoring out physical attraction.
I feel like most of us implicitly know this, but when I see questions asking if there are dating sites to meet these women, it reads to me like the poster doesn't want to actually put in the work in finding a fit woman. There is no magic app, no magic site, no easy and quick way to find a buff woman. You need to get out there, get involved in your local fitness community, go to conventions, attend and/or compete in shows/contests, be friendly and approachable to men and women and for the love of Zuul don't act like a schmoe when you do talk to a muscular woman. Having decent social skills and an approachable demeanor goes a very long way.
Good luck!
I am interested if there are any specific dating sites that fitness or muscle girls use. Are there any dating sites where you can search by bodytype?