Pectoralis muscles are the adductors, flexors of arm in addition to medial rotators of arm. How does this action translate in to acting as helping in push ups or in bench press?
I am having trouble visualizing the primary actions helping in these compound movements.
I also have trouble understanding why this muscle being a powerful adductor does not work in pull up exercise?
The pectoralis major is not just an adductor and medial rotator of the arm. Its clavicular fibres also flex the arm at the glenohumeral joint. This is the action useful in performing push-ups and bench presses.
And yes, its adductor action also plays a role in pull-ups and climbing (along with that of the latissimus dorsi, another adductor).