Postural sway parameters using a triaxial accelerometer: comparing elderly and young healthy adults

Abstract

The purpose of this study was to evaluate the sensitivity of 16 parameters derived from acceleration to detect changes caused by age and visual conditions during quiet standing and detect and minimise possible sources of unwanted variability that could affect accelerometer measures on the trunk. Twenty-seven healthy subjects, including 16 elderly (age, 69.3 ± 3.6 years) and 11 young (age, 23.6 ± 2.2 years) subjects, were evaluated. The parameters evaluated include root-mean-square values, fractal dimensions, path length, range, frequency dispersion and power spectrum among others derived from these values. These 16 parameters evaluated for each axis of movement and/or derivations resulted in 59 sub-parameters. These 59 sub-parameters were analysed in the elderly and young groups and under the open-eye and closed-eye conditions. The results showed that 30 sub-parameters detected differences for an age effect with open eyes, 18 detected differences with closed eyes, 25 detected differences for the young group standing with closed-open eyes and 37 detected differences for the elderly with closed and open eyes (p < 0.01). We used simple signal processing for the accelerometry signals to minimise the effects of unwanted variability that could affect the results. The results showed better performance compared with those results published previously using force platforms to evaluate postural sway. The results presented here should be useful for researchers who want to use accelerometry to evaluate steady postural balance.

Reliability in the Parameterization of the Functional Reach Test in Elderly Stroke Patients: A Pilot Study

“…Moreover, the different registration observed between the lumbar and the trunk sensor (Table 3) confirms that the inertial sensors, in addition to being sensitive, are tools with high specificity. These results are consistent with other studies that have also found inertial sensors as instruments with high sensitivity and specificity [29, 31]. …”

“…These results are in accordance with all the studies consulted [6, 25, 27–31], except the study of Lugade et al [26], which showed reliability levels over 0.9.…”

“…However, these instruments have been used themselves for the kinematic analysis of other tests [6, 25–31], and these were static [27, 31], semistatic [28, 29], or dynamic [6, 25, 26]. …”

Validity and Reliability of Gait and Postural Control Analysis Using the Tri-axial Accelerometer of the iPod Touch

“…The trunk movements are quite small during standing, and although we filtered the data, noise within the frequency range of the movement can influence the outcomes of the parameters, particular the outcomes in the power spectrum. 17 Unfortunately, this type of noise cannot be removed by filters because accelerations related to the movement of the participant will be removed too. 29 The results of the present study indicate that for the test-retest reliability more repeated measurements are needed to obtain reliable estimates for postural control parameters.…”

Compensatory postural adjustments in Parkinson’s disease assessed via a virtual reality environment

“…If a vertical visual motion is evaluated, these data might not be able to properly reflect posture responses [27]. A study, which evaluated outputs from all accelerometers' axis to detect age-related changes in postural balance, detected a great sensitivity of the vertical component for distinguishing young from elderly subjects [44]. This interesting finding, along with the direction of our VR visual stimulus, and also the displacement occurring mainly on the z-axis (Table 2), led to the selection of vertical acceleration for time-frequency analysis.…”