Muscle strain field estimation using object tracking in high definition video sequences

Abstract

Measuring muscle activation is a valuable tool for the determination of diagnostic-focused parameters and the assessment of therapeutic intervention effectiveness. This paper presents a low cost, portable system for estimating muscular strain by measuring local superficial deformation of muscle tissues. Using stereo vision, the 3D positions of a set of markers, placed on the belly of a particular muscle, are estimated to calculate the relative distance between neighbor markers in order to approximate the superficial muscle strain field. This technique was tested on a female subject to measure the deformation of her right quadriceps during a electrical stimulation applied as a 20 Hz train of pulses. The current intensity is from 5 mA to 45 mA, with increasing steps of 5 mA. To validate the system results, the obtained strain fields are evaluated according to their consistency to the force signals resulting from the contractions induced by applied stimuli.