Hi, I think most people think biceps are exclusively used to pull the arm towards your shoulder. However, if you do that motion with your palm facing down, the bicep should be relaxed. It is only when you do that motion with your palm facing you (called 'supinated') that the bicep flexes. In fencing, for example, typically people say to not lift weight, a common thing heard in many martial arts. However, they always, always, always stress the importance of supination of the hand for increasing the point control of the sword. Does else have any examples of people thinking a muscle is used for one thing, but actually it is used more for something else? That is, examples of people misunderstanding muscle function?