What is every muscle used in an arm wrestling competition?

Answer 1

There are several muscles used to actually rotate your arm about the shoulder joint. Here is a list of some of them: pectoralis major, subscapularis, coracobrachialis, biceps brachii, supraspinatus, deltoid, latissimus dorsi, teres major and minor, infraspinatus, long head of triceps.

This is not a complete list of the muscles involved, but what it should say is that this is not a straight forward and simple mechanical motion. The only good (time efficient) exercise is to mimic the arm Wrestling motion--with a cable machine perhaps.

The role of the wrist is also a contributing factor in arm wrestling, but that is much more simple. In this part, the forearm flexors is the muscle that's used.