There's only a handful of true muscular ladies. If you look down the page there is a post about Fitness escorts. One of them is in Vegas. Her reviews are not stellar though. The link doesn't work, but you can still find her by searching Google. Good luck, but I wouldn't get too focused on muscular at the expense of not being able to verify if the provider is really what you are looking to get.

Hi there, I'd love to throw my hat in the ring, I'm 5'11" and lean but strong, feel free to reach out if you think we'd get along!