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The validity of physique-based inverted pendulum models of postural sway behaviour

1980; Informa; Volume: 7; Issue: 2 Linguagem: Inglês

10.1080/03014468000004171

1464-5033

Roger Soames, J. Atha,

Body Composition Measurement Techniques

SummaryOn the grounds that the inverted pendulum model of sway behaviour necessarily implies that sway behaviour will be a linear function of physique, an attempt was made to predict sway behaviour from appropriate individual and composite physique variables. Antero-posterior (Fy) and lateral (Fx) horizontal force components of sway behaviour were recorded for 58 young adults, 29 male and 29 female, using a multicomponent biomechanical measuring platform (Kistler, 9261A). From these records, digitized using an Hewlett Packard Fourier Analyser (HP5451A), a rectified sway impulse was calculated. Height, weight, lean body mass (method of Siri 1956), ponderal index (Hirata 1972) and body surface area (Dubois and Dubois 1916) were also determined for each subject. Correlations between sway magnitude and these physique variables were calculated and appropriate multiple regression equations computed. All correlations were low, with those for the men being consistently lower than those for the women, and all regression equations were of little predictive value.It is concluded that sway behaviour, as estimated by the rectified minute impulse, is essentially independent of physique. Consequently, inverted pendulum models of postural sway are unacceptable, It is postulated that the body behaves as a dynamic counterpoise system in which continuous compensatory movements occur simultaneously and internally between adjacent body segments in such a way that ground reaction forces are not predictably invoked. Being thus balanced, the absolute magnitudes of the segmental masses and the positions of these masses above their supporting base are not important.