Hello chris,a client of mine asked me what activate more the lats
pull up(more then shoulder width grip) or chin up(shoulder width or less)
I answer him that in my opinion it impossible to know because if you do beyond shoulder width the movement on the shoulder is adduction and the main muscle is the Latissimus dorsi and if you do shoulder width or less you have shoulder extension and the main muscle here is also the Latissimus dorsi.
Also if the hand is supinated and your shoulder is in external rotation the lats in their stronger position(and also the biceps).
Maybe there is an EMG research on types of pull-ups and chin-ups? and what do you think about this issue?
Thank you.