Today I wanted to show viewers a difficult excercise to perform along with some coaching cues that will allow you to perform the exercise safely.
As you can see above the Muscle Up is essentially a normal pull up with an explosive element incorporated in order to bring your body above the bar. Muscle ups are a multi-joint movement that primarily work the muscles of your back, core, and to some extent chest and triceps (over the bar phase). They are great because the concentric (upwards) phase of the exercise teaches you how to coordinate an explosive effort and the eccentric (lowering) phase works your lats, core, and forearms much like a pull up.
When doing a muscle up form is key. This move can be abrasive to your joints if you do not do a few important things. First off your initial grip on the bar is very important : Grip the bar with palms facing outwards from you. Unlike a normal pull up you must grip the bar with your palms parallel with the ground as opposed to the wall. Your grip needs to roll over the bar so your wrists are bent over the bar. Initially this will seem awkward but it is crucial the second phase of the exercise or you wont be able to push yourself above the bar.
Beginning at the bottom of a pull up position forcefully pull upwards behind the bar. This is different than a pull up because in a normal pull up you would pull under the bar. As you pull your head and upper torso behind the bar. On your ascent pull forcefully towards the bar and lean into the bar. This will bring you into the bottom of a dip above the bar. Dip just as you would on a dip bar to finish the movement.
This move varies in difficulty. While progressing you can use a kick to generate momentum and make the movement easier. People skilled in muscle ups will be able to perform them very slowly and under control. A muscle up can take a long time to learn depending on your starting strength. For beginners I would advise you to check out a resource like beast skills to learn more.