@article{ref1,
title="Human postural control: assessment of two alternative interpretations of center of  pressure sample entropy through a principal component factorization of whole-body  kinematics",
journal="Entropy (Basel, Switzerland)",
year="2018",
author="Haid, Thomas and Federolf, Peter",
volume="20",
number="1",
pages="e20010030-e20010030",
abstract="Sample entropy (SaEn), calculated for center of pressure (COP) trajectories, is  often distinct for compromised postural control, e.g., in Parkinson, stroke, or  concussion patients, but the interpretation of COP-SaEn remains subject to debate. The purpose of this paper is to test the hypotheses that COP-SaEn is related  (Hypothesis 1; H1) to the complexity of the postural movement structures, i.e., to  the utilization and coordination of the mechanical degrees of freedom; or  (Hypothesis 2; H2) to the irregularity of the individual postural movement  strategies, i.e., to the neuromuscular control of these movements. Twenty-one  healthy volunteers (age 26.4 ± 2.4; 10 females), equipped with 27 reflective  markers, stood on a force plate and performed 2-min quiet stances. Principal  movement strategies (PMs) were obtained from a principal component analysis (PCA) of  the kinematic data. Then SaEn was calculated for the COP and PM time-series. H1 was  tested by correlating COP-SaEn to the relative contribution of the PMs to the  subject specific overall movement and H2 by correlating COP-SaEn and PM-SaEn. Both  hypotheses were supported. This suggests that in a healthy population the COP-SaEn  is linked to the complexity of the coordinative structure of postural movements, as  well as to the irregularity of the neuromuscular control of specific movement  components.<p /> <p>Language: en</p>",
language="en",
issn="1099-4300",
doi="10.3390/e20010030",
url="http://dx.doi.org/10.3390/e20010030"
}