What is hypermobility? Hypermobility is defined as having an unusually or abnormally large range of movement in a joint or joints. It is effectively the opposite of stiffness (hypomobility). A lot of people come to see us because of stiffness, so the thought of hypermobility may sound pretty good, but it comes with it's own host of challenges. Too much movement can be just as problematic as not enough movement!