Hey there everyone! I didn't see a post about this artist yet, but MoxyDoxy is a fantastic artist in the realms of DA and FurAffinity, specializing in muscle growth, among other things.
You can find a link to her gallery
here. WARNING: She also does work with futacocks and extreme boob/lips as well. So if you're easily offended by any of those things, ye be warned.
Here's a link to a sample of her muscle growth stuff.
http://img03.deviantart.net/337f/i/2...xy-d8yqpa1.jpg