Chin up Palms supinated The prime movers :-biceps brachii- latissimus dorsi-ters major-brachialisstabilizers :-biceps brachii- triceps ( long head ) synergists : -brachialis-brachioradialis- teres major -posterior deltoid- rhomboid -levator scapula-lower trapezius -levator scapula-pectoralis minor-lower trapizus-pectoralis major ( sternal )  I did as many chin-up as possible and the muscle that will inhibit my ability to perform more repetition is the ( biceps brachii ) because it is not a large muscle like the latissimus dorsi  The chin-up is an effective exercise for the latissimus dorsi because when you used the supinated grip there is extension in the shoulder joint with the pronated grip when its wider than shoulder width , the elbows joint out to the sides allowing shoulder joint adduction to take place , each of these actions involves different portions of the same muscles  Many variations of pull – ups and chin-ups :-under hand chin-ups-pull over cable-rear pull down-straight arm pull