All of this information is useless unless we understand what it all sums up to for us in the gym. Due to the attachments and orientation of this muscle and the many movements it performs the Lats play a crucial role in force transfer between the lower and upper body as well as key roles in core stability at the lumbar spine and breathing patterns. This is why it is important to develop the lats properly and pull-ups are one of the greatest exercises for this purpose.
But hold on before you head to the gym and start ripping away on the pull-up bar let me finish and hear me out because I think there are a few big considerations we need to address regarding development of the lats and excessive pull-uping (I know I am such a wordsmith).
First thing to consider and remember is that the lats are bigger and stronger that the traps and will therefore always overpower the traps. Due to this overpowering influence the lat possesses in addition to its role in extending the spine overly developed lats can often lead to gross extension patterns in many peoples posture (many individuals already hang around in a lordotic posture so this would compound their existing issue). This type of extension pattern is marked by a distinct rib flair and sometimes excessive internal rotation of the humerus due to a lack of effort by the traps to pull the shoulder blades back and down against the rib cage. And this tug of war between the traps and the lats seems evenly matched from the surface but when the cross sectional area of both muscles is taken into account one can see why the lats always win out. This struggle is caused to sway even more towards the lats when they are constantly being given priority in a training program. Ideally one wants to learn to move the scapula against the rib cage instead of extending the entire spine.
Second and last thing to consider before hitting pull-ups often and hard is to understand that overly developed lats can decrease the amount of base below the acromial which can lead to irritation when trying to perform overhead movements. Remember for previous reading that the lat extends, adducts, and internally rotates the humerus and to achieve an overhead motion correctly one needs to perform flexion, abduction, and external rotation meaning the lat is a direct antagonist to overhead motion. The biggest prime movers involved in the three motions needed for overhead pressing are the deltoid, lower trapezius, and posterior rotator cuff and when all three of these muscles's cross-sectional area is compared with the lats cross-sectional area we can see that again overly developed lats will win every single time.
My point for this post is not to say that pull-ups are bad for you because that is far and away from the truth. The truth being that pull-ups are a great exercise that does an effective job at developing the lats and should be used in appropriate volume and intensity along side a number of other movements to insure postural balance and limited dysfunctional movement. My goal of this post was to simply introduce two big considerations one should remember if they are doing a lot of pull-ups. That way an individual can take steps to insure neither of the two contraindications occur.