Recurrence Quantification Analysis in Accelerometric Signals of the Rectus Femoris during Quiet Stance

Postural control involves the activity of three physiological systems, visual, vestibular, and proprioceptive. Galvanic vestibular stimulation (GVS) is a noninvasive method that activates the vestibular system and its related physiological pathways. This study aimed to determine the effect of GVS (perturbation) on the human balance system. We used accelerometric sensors to record postural oscillations before and during bilateral bipolar GVS. Accelerometry was recorded from 9 healthy subjects that stood for 60 seconds in two conditions: without and with GVS. Stimulation current ranged from 0.1–1 mA. The accelerometric sensor was placed over the rectus femoris, a postural muscle, and subsequently, signals were analyzed by a recurrence quantification analysis (QRA). No significant differences were found between the conditions. However, the qualitative and quantitative RQA showed a quasi-periodic-chaotic system behavior. RQA proved to be a valuable tool to describe postural performance according to sensory input.