Methods for Sitting Posture Evaluation: Static Posture and Applications

Pressure sores (PS), are frequent in subjects with spinal cord injuries, and to minimize PS these subjects must get used to frequently changing their posture; useful information to this aim may come by testing healthy subjects and studying their kinematic behaviour during long sitting sessions. Two different investigation systems have been developed to this aim in the Department of Mechanics and Aeronautics (DMA) of Rome University ‘‘La Sapienza’’: the two systems, a pressure map sensor arranged on a chair and a potentiometer-based device to measure trunk rotations at the base of the spine are shown in this paper and their outputs are compared and correlated. The behaviour of ten healthy subjects is then evaluated during a one hour sitting session for preliminary consideration: there is a postural change every 7.7 ± 6.7 minutes in the frontal plane and every 5.7 ± 2.7 minutes in the sagittal plane; pelvis movements can be resumed by Centre of Pressure (COP) displacements and the largest values of these displacements are 5.2 ± 2.4 cm in the frontal plane and 3.0 ± 1.4 cm in the sagittal plane; the largest rotations in the two planes are respectively 8.4 ± 0.7 and 20.7 ± 12.6. The results of the study are discussed and satisfactorily compared with literature results

A Facility for the Study of Pelvis and Trunk Displacements during Sitting Posture

1475-1305.2008.00606.

Single-stance posture analysis by means of a contact resistance variation pressure array sensor

Padov

A novel pressure array sensor based on contact resistance variation: Metrological properties

The working principle and the metrological performances of a novel array sensor devoted to pressure map measurements are experimentally analyzed here. The physical principle on which the sensor elements are sensitive to the pressure is the variation of the contact resistance. Pressure maps from 1 up to 500 kPa can be measured. The prototype here utilized for the metrological characterization has been an 838 matrix sensor with a 5 um spatial resolution over both x and y direction and a total thickness of 150 um. The materials that have been chosen to assemble the prototype yielded to a very flexible and robust sensor which can easily be fitted over round surfaces without being damaged or leading to an alteration of its measuring properties. The static and the dynamic metrological performances of the sensor that have been studied and discussed are the response function and the calibration curve, the repeatability, the sensitivity, the time drift, the hysteresis, and the dynamic response. In spite of its functional and constructive simplicity, the metrological performances the sensor has exhibited, together with its peculiar constructive feature, have indicated the possibility to utilize it to effectively measure pressure maps in every application for which the sensor could be shaped in

Decline of physical and cognitive conditions in the elderly measured through the functional reach test and the mini-mental state examination

There are several tests used to evaluate the psychophysical characteristics of the elderly and, of these, the most suitable are the functional reach (FR) test, an index of the aptitude to maintain balance in an upright position, and the mini-mental state examination (MMSE), a global index of cognitive abilities. The sample of elderly people we analyzed involved 50 healthy subjects divided into three age-groups (15 subjects from 55 to 64 years, 19 from 65 to 74 years, and 16 over 75 years of age); they underwent an FR test, which consists first in the measurement of the anthropometric characteristics, then in the execution of the test itself, and finally in the study of the upright posture by the analysis of the center of pressure (COP) trend; they underwent an MMSE as well to evaluate the main areas of the cognitive function concerning space-time orientation, short-term memory, attention ability, calculation ability and constructive praxis. The results of these tests show, according to the age of the subject, a loss of physical performance (FR, FR related to height, and COP displacement), as well as a loss of cognitive abilities; however, in all cases the only significant changes are those between the first and the other two age-groups. Finally, a comparison between FR and MMSE shows a more rapid decline of physical performance compared to cognitive performance. (C) 2009 Elsevier Ireland Ltd. All rights reserved