Harder Than It Looks
Pull-ups? No problem for you. Dips? Easy. But each time you attempt a muscle-up, which looks like a simple combination of a pull-up and a dip, you hit a brick wall. What's going on?
A muscle-up seems easy enough. Get really good at pull-ups and dips, then find a bar or a set of rings. Do a pull-up, follow it with a dip, and you'll have done a muscle-up. Unfortunately, it usually doesn't happen that easily.
First, don't associate a muscle-up with a pull-up. In karate, you're taught to think "through" a board in order to break it. The same thing applies to the bar during a muscle-up – think through it. If you only pull yourself to the bar you'll never get high enough to transition into a dip.
Here's where the bar is relative to your body at the end of a pull-up:
This position is far from where you need it to be in order to complete a muscle-up. For a successful muscle-up, the position of the bar will look more like this:
Notice that the bar has been pulled all the way to the bottom of the chest. This will be a good position to complete a muscle-up from. If you initiate a muscle-up by simply doing a pull-up, you'll only get to the bar, not "through" the bar.
Elbow Position: Pull-Up vs. Muscle-Up
A pull-up is complete when the elbows are driven completely down. With your elbows down, it will be impossible to transition into a dip.
If you cue yourself to pull through the bar, you're much more likely to be able to get your elbows rotated around the bar. This will put you in position to complete a muscle-up with a dip.
How To Pull
You'll need to apply two different forces to the bar. If you sequence these forces correctly with enough power, the bar and your elbows will be positioned accordingly.
First, pull the bar down. This closely resembles a pull-up and is what will help peak your body above the bar. Right after initiating the pull, begin to push the bar down. This will help guide the bar to the bottom of your chest and most importantly, start to rotate your elbows around the bar.
Note the two different types of pulls in the video below. The left shows the pull that's described above, while the right shows a simple pull-up.
Muscle-Up: Types of Pulls
When you approach the bar to do a muscle-up, ditch the pull-up motor pattern. A muscle-up is an entirely different exercise that requires an entirely different pull.