Equimetrix Device: Criteria Based Validation and Reliability Analysis of the Center of Mass and Base of Support of a Human Postural Assessment System.

Pedro Fonseca,Pierre Barralon,Ricardo Sebastião,Igone Idigoras,Manoela Sousa,Filipa Sousa,João Paulo Vilas-Boas,Márcio Goethel,Leandro Machado

doi:10.3390/s21020374

Abstract

Human postural control is a fundamental ability for static and dynamic tasks, especially in hiper- and hipo-functional populations, such as the elderly. The Equimetrix is a clinical device developed to assess both the base of support (BoS) and the center of mass (CoM) dynamics, thus allowing their use as new evaluation and training tools. This study aims to perform a criteria based validation of Equimetrix by comparing the BoS and CoM data with gold-standard equipment. A motion capture system, force platform, and pressure mat were used to calculate the CoM, center of pressure (CoP) and BoS during bipedal, unipedal, feet together and full tandem stances. Results demonstrate an excellent reliability of Equimetrix in terms of spatial accuracy of the CoM, although over-estimating the CoM height. Differences were found when comparing Mean velocity Path with the CoM, but not with the CoP, indicating a lower reliability in time-based parameters. The Equimetrix presents a tendency to overestimate the BoS, with mixed reliability values, which may be related to the different size of sensing elements between the Equimetrix and the pressure sensing mat. These are encouraging results that should be further explored during dynamic tasks.

Highlights

The ability to maintain balance is a necessary requirement for static and dynamic postural control in humans and is considered a key element in daily living and sports activities [1,2]
The purpose of this study is to evaluate how the Equimetrix device performs in terms of determination of different bases of support, and if it can be reliably used as a postural control measuring system in humans, by comparing its measurements to center of mass (CoM), center of pressure (CoP), and base of support (BoS) data retrieved from gold standard system and using common stabilogram and statokinesigram parameters as validation criteria
This means the CoM sway is identically measured by both systems, albeit the higher Equimetrix center of mass (E_CoM) value, which may lead to an overestimation of the AP and ML displacement

Summary

Introduction

The ability to maintain balance is a necessary requirement for static and dynamic postural control in humans and is considered a key element in daily living and sports activities [1,2]. This is a complex process regulated by the nervous, visual, vestibular, and motor systems, which are responsible for the transmission of the necessary information to the somatosensory system in order to trigger an adequate motor response [1,3]. Not all causes of fall can be solved with training, the application of physical exercises, including proprioceptive and balance training, has shown evidence of a positive effect in fall prevention [5]

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