What is the meaning of "wind up"?
Native speaker’s answer
Rebecca
"Wind up" in this case refers to the motion of his arm spinning in circles to prepare to throw the baseball a long distance. This is a common expression used in baseball to describe this action before pitching a ball. The expression "wind up" can also be used to refer to most anything that spins or needs to be turned to work. Ex: If you wind up the music box, it will play a song.