Version 1
: Received: 22 July 2024 / Approved: 23 July 2024 / Online: 24 July 2024 (07:05:31 CEST)
How to cite:
Wesley, J.; Rhodes, S.; Zeitler, D. W.; Alderink, G. Approximate and Sample Entropy of the Center of Pressure during Unperturbed Tandem Standing: Effect of Altering the Tolerance Window. Preprints2024, 2024071839. https://doi.org/10.20944/preprints202407.1839.v1
Wesley, J.; Rhodes, S.; Zeitler, D. W.; Alderink, G. Approximate and Sample Entropy of the Center of Pressure during Unperturbed Tandem Standing: Effect of Altering the Tolerance Window. Preprints 2024, 2024071839. https://doi.org/10.20944/preprints202407.1839.v1
Wesley, J.; Rhodes, S.; Zeitler, D. W.; Alderink, G. Approximate and Sample Entropy of the Center of Pressure during Unperturbed Tandem Standing: Effect of Altering the Tolerance Window. Preprints2024, 2024071839. https://doi.org/10.20944/preprints202407.1839.v1
APA Style
Wesley, J., Rhodes, S., Zeitler, D. W., & Alderink, G. (2024). Approximate and Sample Entropy of the Center of Pressure during Unperturbed Tandem Standing: Effect of Altering the Tolerance Window. Preprints. https://doi.org/10.20944/preprints202407.1839.v1
Chicago/Turabian Style
Wesley, J., David W. Zeitler and Gordon Alderink. 2024 "Approximate and Sample Entropy of the Center of Pressure during Unperturbed Tandem Standing: Effect of Altering the Tolerance Window" Preprints. https://doi.org/10.20944/preprints202407.1839.v1
Abstract
Approximate entropy (ApEn) and sample entropy (SampEn) are statistical indices designed to quantify the regularity or predictability of time series data. Although ApEn has been a prominent choice for use in the analysis of non-linear data, it is currently unclear as to which method and parameter selection combination is optimal for its application in biomechanics. The goal of this research was to examine the differences between ApEn and SampEn related to center of pressure (COP) data during tandem standing balance tasks, while also changing the tolerance window, r. Six participants completed five, 30-second trials, feet-together and tandem standing with eyes-open and eyes-closed. COP data (fs = 60 Hz, downsampled from 1200 Hz) from ground reaction force platforms were collected. ApEn and SampEn were calculated using a constant vector length, i.e., m = 2, but differing values of r (tolerance window). For each of the participants, four separate one-way analysis of variance analyses (ANOVA) were conducted for ApEn and SampEn in the anterior-posterior (AP) and medial-lateral (ML) directions. Dunnett's intervals were applied to the one-way ANOVA analyses to determine which tandem conditions differed significantly from the baseline condition. ApEn and SampEn provided comparable results in the predictability of patterns for different stability conditions, with increasing instability, i.e., tandem eyes closed postures, being associated with greater unpredictability. The selection of r had a relatively consistent effect on mean ApEn and SampEn values across r = 0.15 * SD to r = 0.25 * SD, where both entropy methods tended to decrease as r increased. Mean SampEn values were generally lower than ApEn values. The results suggest that both ApEn and SampEn indices demonstrated relative consistency and were equally effective in quantifying the level of the center of pressure signal regularity during quiet tandem standing postural balance tests.
Keywords
approximate entropy; sample entropy; tandem standing balance; center of pressure; complexity; tolerance; nonlinear time series; downsampling
Subject
Engineering, Bioengineering
Copyright:
This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
