THETAmetrix were asked to write a MATLAB algorithm to achieve a specific demand relating to a project measuring movement irregularity. The ‘problem’ and ‘solution’ was outlined to THETAmetrix in consultation, following which a MATLAB algorithm was written to meet these aims.

A plot of the motion of lumbar spine flexion is shown below. This graph plots angular velocity against angular displacement to represent the movement in the spatial domain – illustrating movement trajectory. The irregularity of movement was defined as deviation from a predicted ‘smooth’ motion (black dotted line). This deviation can be seen in particular at the end of quartile 2 and beginning of quartile 3 on the graph. The degree of irregularity was quantified to yield a single value of irregularity (RMS difference) for each quartile of the movement.

For more information see: Williams, JM, Haq, I, Lee, RY. 2011. A novel approach to the clinical evaluation of differential kinematics of the lumbar spine. Chartered Society of Physiotherapy Congress, Liverpool, UK. Note: Login required (but free).