Muscle-ups are basically just a kip > straight arm push-down > dip. They're an impressive trick, but it's more getting the groove / technique down. If you can do ten pull-ups, you can do a muscle-up. Far as cross-fit goes... I've incorporated several aspects at different times over the years. I'll drill compound lifts in intervals at like 55% or less. Point there is getting in the repetition, especially with the Ollie lifts. Just honing the fuck outta the movement patterns. It's where I picked big time on circuits and giant sets. Both completely changed the game for me and shaped my overall training style immensely. Started learning a ton of PT and mobility drills as well. Huge difference when I'm patient enough to actually do them consistently. Lol. The biggest reason CF has blown up is really just because it's super accessible though. Powerlifting and bodybuilding have kind of an intimidating air about them that can make the sports a kind of unapproachable to the uninitiated. More women getting into both and going mainstream is helping change that. But...its still going to take some time and I don't think either will ever reach CF mainstream status. I do kind of see strongman blowing up in the next decade though. It's got that same kind of approachability about it. Who h is super cool. Post script: Everyone that PL's or BB's seriously will eventually injure themselves. It's part of the game when you're moving several hundred pounds through three dimensions on a regular basis. I could just as easily point to a high rate of injury among yoga practitioners. Especially a few years back when it really blew up. Nobody can argue the value of dedicated practice, unless they're a complete fuck-wit, but unqualified instructors get people hurt. Sometimes seriously. Generally they're the irresponsible cash grabbers that don't take the time to find and address dysfunction. That or they aren't strong willed enough to not cave to clients that just want to jump to the "fun" stuff.