3×0:30 Box Shoulder Stretch
Place your arms shoulder width apart on a 20″-24″ box. Keeping your head neutral (look at the floor, don’t bury your chin in your chest) push your shoulders open as far as possible driving your head and chest to the floor. The stretch should come from your shoulders and thoracic spine, not your lumbar spine. Again, be patient. You’ll probably look more like the lower image than the upper image when you start out.
3×10 PVC Shoulder Raises
Lay stomach down on the floor with perfectly straight knees and pointed toes. Hold a PVC pipe in front of you shoulder width apart. Keep your nose on the ground and raise your arms up as high as possible. Take your time with this movement, and fight to keep your elbows locked out. Mastering this stretch is going to be the easiest way to improve your muscle ups. Trust me.
Skills and Drills
3×30′ Pike to Hollow Inch Worms
Begin in a toe-touch position, keeping your feet still walk your hands out to a hands and feet hollow hold position. Pause in the hollow then keep your hands still and walk your feet in. Work on stretching your hamstrings and also quickly finding the hollow body shape.