Research article summary (published 12 Feb 2004):

Is perception of upper body orientation based on the inertia tensor? Normogravity versus microgravity conditions.

Full Abstract

During lateral leg raising, a synergistic inclination of the supporting leg and trunk in the opposite direction to the leg movement is performed in order to preserve equilibrium. As first hypothesized by Pagano and Turvey (J Exp Psychol Hum Percept Perform, 1995, 21:1070-1087), the perception of limb orientation could be based on the orientation of the limb's inertia tensor. The purpose of this study was thus to explore whether the final upper body orientation (trunk inclination relative to vertical) depends on changes in the trunk inertia tensor. We imposed a loading condition, with total mass of 4 kg added to the subject's trunk in either a symmetrical or asymmetrical configuration. This changed the orientation of the trunk inertia tensor while keeping the total trunk mass constant. In order to separate any effects of the inertia tensor from the effects of gravitational torque, the experiment was carried out in normo- and microgravity. The results indicated that in normogravity the same final upper body orientation was maintained irrespective of the loading condition. In microgravity, regardless of loading conditions the same (but different from the normogravity) orientation of the upper body was achieved through different joint organizations: two joints (the hip and ankle joints of the supporting leg) in the asymmetrical loading condition, and one (hip) in the symmetrical loading condition. In order to determine whether the different orientations of the inertia tensor were perceived during the movement, the interjoint coordination was quantified by performing a principal components analysis (PCA) on the supporting and moving hips and on the supporting ankle joints. It was expected that different loading conditions would modify the principal component of the PCA. In normogravity, asymmetrical loading decreased the coupling between joints, while in microgravity a strong coupling was preserved whatever the loading condition. It was concluded that the trunk inertia tensor did not play a role during the lateral leg raising task because in spite of the absence of gravitational torque the final upper body orientation and the interjoint coupling were not influenced.

Author information

Author/s: Gueguen, N (N); Coyle, T (T); Craig, C (C); Bootsma, R (R); Mouchnino, L (L);

Affiliation: Laboratoire Mouvement et Perception, Faculté des Sciences du Sport, CNRS-Université de la Méditerranée, 163 avenue de Luminy, 13288 Marseille cedex 9, France. gueguen(-atsign-)laps.univ-mrs.fr

Journal and publication information

Publication Type: Journal Article; Research Support, Non-U.S. Gov't

Journal: Experimental brain research. Experimentelle Hirnforschung. Expérimentation cérébrale (Exp Brain Res), published in Germany. (Language: eng)

Reference: 2004-Jun; vol 156 (issue 4) : pp 471-7

Dates: Created 2004/05/28; Completed 2004/09/29; Revised 2009/11/11;

PMID: 14968277, status: MEDLINE (last retrieval date: 11/11/2009, IMS Date: )

Sourced from the National Library of Medicine. Abstract text and other information may be subject to copyright.

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MeSH headings (categories)

This article was linked to the MESH Headings shown below.

Adult Biomechanics Extremities - innervation; physiology Gravity Sensing - physiology Humans Joints - innervation; physiology Male Models, Neurological

Models, Neurological Movement - physiology Orientation - physiology Posture - physiology Proprioception - physiology Torque Weight-Bearing - physiology Weightlessness Simulation

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