Arguably, when we talk about biomechanics in a clinical sense there is a tendency to use 'qualitative' descriptions of motion, i.e.: planes of motion, ranges of motion. As clinicians or therapists, we describe qualities in a client's movement (i.e.: limited ROM, hyperextension, stiffness, etc). The intended outcome is often to categorise movement as either 'good' or 'bad', and/or to use these to explain a pain or injury. The main aim is for the output to inform our treatment/intervention selection.