SOME PARAMETERS OF MULTI-LOOP BIOFEEDBACK CONTROL OF POSTURE

Abstract

In the present study the displacements of centre of pressure as well as the vertical projection of centre of mass, the time functions on anteroposterior and mediolateral directions and Fourier spectra have been recorded in traditional and/or sharpened Romberg position, with open and closed eyes. Special track tasks with voluntary moving of centre of pressure have been solved by the subjects with audiovisual feedback. Many researchers have investigated the displacements of centre-of-pressure /Diener 1984, Peein 1989, Boloban 1990, Laputin et al 19901. Posture characteristics and evoked brain potentials have been recorded to investigate afferent and efferent functions /Ackermann et a1 1986, 19901. New mathematical techniques from statistical mechanics are developed to the analysis of stabilograms /Collins and De Luca 19931 The maintenance of equilibrium to most sport movements. b!, the control of the body segments, the motor behaviour, the posture dynanlics and stability. suggests to investigate special parameters and levels of balance on sportsmen before and after exercise. In our experiments 28 subjects. from different sport kinds. as \\-ell as secondary students /age: 12 - 22 years/ were tested. The equipment we used to investigate the equilibrium in the traditional and sharpened Romberg situations included "Adam" type force platform. ADDON micro-computer. connected via RS 232 interfacing to personal computer. Excerpts of results /engineer candidates/: Romberg test: radius of characterising circle I68 %/ rl = 4 mm (open eyes). r2 = 5.3 mm (closed eyes). Sharpened Romberg test: r3 = 6,3 mm (open). r4 = 71 mm (closed). Dominant frequencies in the Fourier spectra (individual): mediolateral 1x1: 0.05 - 0.1 & 0.6 - 0.7 Hz. as \\ell as anteroposterior ,'Y!: 0,3 - 0.4 & 1 - 1.6 HZ.