Arm wrestling is a sport

Sport

A Sport is all forms of physical activity which, through casual or organised participation, aim to use, maintain or improve physical fitness and provide entertainment to participants. Sport may be competitive, where a winner or winners can be identified by objective means, and may require a degree...

 with two participants. Each participant places one arm (either the right or left, but both must be the same) on a surface with their elbows bent and touching the surface, and they grip each other's hand. The goal is to pin the other's arm onto the surface, with the winner's arm over the loser's arm.
Various factors can play a part in one's success in arm wrestling.