Diagonal pulls is an exercise where you work the extensor chain of the shoulder. Because of the stabilising work for the shoulder depressors in this combined extension, abduction and external rotation, you can work the arm to around or slightly above 90° angle with less risk of gliding the head of the upper arm upward into the ceiling and squeezing the structures in-between.

Always consider your posture in every exercise. A stately posture with an active core is what we want to see!