title: Postural Stability Margins as a Function of Support Surface Slopes.
abstract: This investigation examined the effects of slope of the surface of support (35°, 30°, 20°, 10° Facing(Toe) Down, 0° Flat and 10°, 20°, 25° Facing (Toe) Up) and postural orientation on the margins of postural stability in quiet standing of young adults. The findings showed that the center of pressure-CoP (displacement, area and length) had least motion at the baseline (0° Flat) platform condition that progressively increased as a function of platform angle in both facing up and down directions. The virtual time to collision (VTC) dynamics revealed that the spatio-temporal margins to the functional stability boundary were progressively smaller and the VTC time series also more regular (SampEn-Sample Entropy) as slope angle increased. Surface slope induces a restricted stability region with lower dimension VTC dynamics that is more constrained when postural orientation is facing down the slope. These findings provide further evidence that VTC acts as a control variable in standing posture that is influenced by the emergent dynamics of the individual-environment-task interaction.
authors.affiliation: Department of Kinesiology, The Pennsylvania State University, State College, PA, United States of America.
authors.forename: Aviroop
authors.identifier: http://orcid.org/0000-0002-6256-0578
authors.initials: A
authors.lastname: Dutt-Mazumder
authors.affiliation: Department of Kinesiology, The Pennsylvania State University, State College, PA, United States of America.
authors.forename: Seymon M
authors.initials: SM
authors.lastname: Slobounov
authors.affiliation: Department of Kinesiology, The Pennsylvania State University, State College, PA, United States of America.
authors.forename: John Henry
authors.initials: JH
authors.lastname: Challis
authors.affiliation: Department of Kinesiology, University of Georgia, Athens, GA, United States of America.
authors.forename: Karl Maxim
authors.initials: KM
authors.lastname: Newell
mesh_terms: D000328:Adult; D001696:Biomechanical Phenomena; D006801:Humans; D008297:Male; D004856:Postural Balance / Q000502:physiology*; D011187:Posture / Q000502:physiology*; D013997:Time Factors; D055815:Young Adult