I am a little confused regarding an issue that keeps coming up in discussion when I talk with some personal trainers. The issue is whether you should set the scapula when you perform a lat pull down or a chin up. I attended a seminar by Paul Chek in which he said there was a study done about this topic, and the study concluded that during the first 10 degrees of movement in an exercise the scapula sets itself. Any information about this would be much appreciated!
When the shoulder undergoes 180 degrees of abduction and adduction during the lat pull down, 60 degrees of this movement will come from the scapula as it rotates up and down on the thorax. Therefore, if we attempt to set the scapula prior to shoulder adduction, even though this may engage the often under-active lower trapezius, it will increase the stress placed on the shoulder complex by unnaturally restricting scapula movement. I believe that if you are going to set the scapula, it has to be performed in isolation. Scapula setting can serve as a weak link activation exercise that will strengthen the lower trapezius to resist the pull of the upper trapezius during shoulder movements. Once a level of strength and balance has been achieved, you can start to incorporate more integrated movements like lat pull downs into a program. Also, any attempt to free the scapula in the frontal plane is only going to improve matters, so often I will manually assist the scapula in upward and downward rotation while my client performs side arm raises. Stretching out the often over-active upper trapezius and pec minor prior to this may also help free the shoulder complex up a little.