The term motion implies the capability that you have to move your joint in various directions. There are a number of things that determine it. The most fundamental among these is how the inner parts of your joints are working. Also important in this case are the structures that surround it. When you stretch on a regular basis you can be sure that you will be able to perform a wider range of motion. If you wish to know how stretching can help with these structures the first thing that you need to do is be familiar with them. You also need to know in this context as to how they can help the movement of a joint or hinder it.