Preparation for chin up

Height rings: highest point of ring nippel-hight so as you contract your hands touch your lower ribs 

Ellbows close to your sides 

Hang diagonal with your feet on the ground as low under as you can (less diagonal is easier)

Arms straight, activate the shoulders, palms facing posterior 

Explode towards contracting the arms, driving the sternum up while turning the palms to medial

Excentric going back to straight arms slowly counting to three while turning the hands again to starting position

Shortly relax the shoulders 

Begin again by activating the shoulders

10-15 reps

3 sets