One of the reasons to practice Nei Jia is to optimise your movement. Optimisation of movement means that the range of movement becomes smaller. If we take this to its logical conclusion, then the simplest movement must be no movement at all...Something must be wrong here! One of the key characteristics of Nei Jia is spiral motion. The gross movement we make with a limb must be spiral, together with the movement around each joint. So, we simplify gross movement but the complexity of the movements around each joint increases. As we actually increase the complexity of the movement around our joints we can feel the restrictions within this movement. Introducing spiral motion within our joint movement not only stretches the connecting muscles in a non-linear way but also sends lubrication to the joints, thereby going some way to actually restore free joint mobility. This is one of the reasons why Nei Jia must comprise of constant motion. Tai Chi, in particular (and Nei Jia in general) is designed to implement non repetitive motion that systematically engages every active joint in the body to this complex, spiral motion.