Biomechanical analysis of human standing: studies about balance control

Author(s)

Luis Mochizuki

• Document type: Doctoral Thesis
• Press: São Paulo.
• Institution: Universidade de São Paulo (USP). Escola de Educação Física e Esportes (EEFE/BT)
• Defense date: 2002-01-17

Examining board members

Alberto Carlos Amadio; Gil Lúcio Almeida; Aluisio Otávio Vargas Ávila; José Angelo Barela; Go Tani

• Advisor: Alberto Carlos Amadio

Abstract

The main idea of this Thesis is a biomechanical approach to ol. Static and dynamical posturography are used to study human standing. Static posturography is the procedure to measure center of pressure excursions during one and two legged quiet postures for the Experiment 01. By the use of dynamical posturography, we study the postural adjustments produced by fast knee flexion, the focal movement. Experiments 02 and 03 are cononducted under this procedure. The results of Experiment 02 are used to describe and analyze the effects of the focal movement on center of pressure for each support. The Experiment 03 is designed to study the effect of gymnastics practice in postural adjustments. In relation to the conceptual problem proposed for Experiment 01, expressed by the question: which are the postural strategies described by center of pressure and what factors affect them? Different strategies are described by looking at center of pressure results. During one-legged posture, the more difficult posture, the more effect of sensory constraints is observed. The results underlies about postural control during standing and possible postural strategies associated to foot position. In relation to the conceptual problem proposed for Experiment 02, expressed by the question: which are the postural adjustments during leg thigh levation and what factors affect them? The anticipatory postural adjustment changes according to the experimental groups. The task repeated five times is correlated to anticipatory response for some adults. The results are used to describe the contribution of each support for the postural adjustments due to leg movements. In relation to the conceptual problem proposed for Experiment 03, expressed by the question: how are postural adjustments for gymnasts? The anticipatory and compensatory postural adjustments are different according to the experimental groups. Gymnasts show less oscillation during postural adjust ments. he relation between variables is affect by group. The results are estimations about the number of dimensions associated to experimental data and we discuss the degrees-of-freedom problem. At last, to answer the main question: we consider that postural adjustments identify modifications in postural control, and is affected by age, levei of motor experience, and individual inertial characteristics. The postural adjustments adaptation to a specific task may be a tool to evaluate the ability to control balance. It may have a complex structure that rules postural adjustments based on the common control of independent variables. We believe that such our approach to posture control may offer issues to discuss how experiences on equilibrium tasks enhance balance (AU)