Phase plane analysis of stability in quiet standing

• Published in: Journal of rehabilitation research and development Vol. 32; no. 3; pp. 227 - 235
• Main Authors: RILEY, P. O, BENDA, B. J, GILL-BODY, K. M, KREBS, D. E
• Format: Journal Article
• Language: English
• Published: Baltimore, MD Rehabilitation Research and Development Service 01.10.1995; Superintendent of Documents
• Subjects: Biological and medical sciences; Ear, auditive nerve, cochleovestibular tract, facial nerve: diseases, semeiology; Gravitation; Humans; Medical research; Medical sciences; Models, Statistical; Motor ability; Non tumoral diseases; Otorhinolaryngology. Stomatology; Postural Balance - physiology; Rehabilitation; Space life sciences; Human; Center; Vestibular function; Disease; Center of mass; Balances; Equilibrium; Pressure; Comparative study; Posture
• ISSN: 0748-7711; 1938-1352

We analyzed the standing balance control of 11 healthy subjects and 15 subjects with bilateral vestibular hypofunction (BVH) using phase plane (velocity versus displacement) plots. We hypothesized that maintaining postural stability requires control of both the position and momentum of the center of gravity (CG) and infer that it is advantageous to use both velocity and displacement data to characterize balance control. Phase plane plots provide insight into this dynamic aspect of balance control. We evaluated phase plane plots based on whole body CG and center of pressure (CoP). We varied stability by altering the base of support and visual information. Three different foot placements were used: feet wide apart, feet together, and semitandem stance. Feet together standing was performed with eyes open and with eyes closed. The phase plane plots show changes in stability as base of support is altered or visual input is removed and reveal stability differences between the control and BVH groups. The root mean square variance of velocity and displacement was used to quantify the phase plane information. This parameter showed significant differences between activities and between groups. We conclude that phase plane plots that combine displacement and velocity information are more useful in characterizing balance control than displacement or velocity alone.