Two simple yet commonly overlooked tools/progressions for pull up strength (and pull strength in general) are the use of the Eccentric pattern and the Fat Grip overload to the forearm and palm flexors (pictured is the Fat Gripz tool).
The primary benefits we are seeing:
1. Increased grip strength and load decreases the likelihood the individual will use a weight that will cause pain or dysfunction
2. Increasing grip strength creates a stronger message to scapular stabilizers to “hold on” and produce more stability in the glenohumeral joint.
3. Exposing the body to the eccentric load can allow the individual to increase volume (especially as appropriately integrated into a periodized model of isometric holds, eccentric reps and finally moving to full eccentric to concentric reps)