title: Real-time visual feedback of COM and COP motion properties differentially modifies postural control structures.
abstract: The experiment was setup to investigate the control of human quiet standing through the manipulation of augmented visual information feedback of selective properties of the motion of two primary variables in postural control: center of pressure (COP) and center of mass (COM). Five properties of feedback information were contrasted to a no feedback dual-task (watching a movie) control condition to determine the impact of visual real-time feedback on the coordination of the joint motions in postural control in both static and dynamic one-leg standing postures. The feedback information included 2D COP or COM position and macro variables derived from the COP and COM motions, namely virtual time-to-contact (VTC) and the COP-COM coupling. The findings in the static condition showed that the VTC and COP-COM coupling feedback conditions decreased postural motion more than the 2D COP or COM positional information. These variables also induced larger sway amplitudes in the dynamic condition showing a more progressive search strategy in exploring the stability limits. Canonical correlation analysis (CCA) found that COP-COM coupling contributed less than the other feedback variables to the redundancy of the system reflected in the common variance between joint motions and properties of sway motion. The COP-COM coupling had the lowest weighting of the motion properties to redundancy under the feedback conditions but overall the qualitative pattern of the joint motion structures was preserved within the respective static and dynamic balance conditions.
authors.affiliation: Department of Kinesiology, The University of Georgia, 330 River Rd, Athens, GA, 30602, USA. mck18@uga.edu.
authors.forename: Melissa C
authors.initials: MC
authors.lastname: Kilby
authors.affiliation: Department of Human Development and Family Studies, The Pennsylvania State University, 315 Health and Human Development East, University Park, PA, 16802, USA.
authors.forename: Peter C M
authors.initials: PC
authors.lastname: Molenaar
authors.affiliation: Department of Kinesiology, The Pennsylvania State University, 276 Recreation Building, University Park, PA, 16802, USA.
authors.forename: Semyon M
authors.initials: SM
authors.lastname: Slobounov
authors.affiliation: Department of Kinesiology, The University of Georgia, 330 River Rd, Athens, GA, 30602, USA.
authors.forename: Karl M
authors.initials: KM
authors.lastname: Newell
mesh_terms: D000328:Adult; D001696:Biomechanical Phenomena; D056228:Feedback, Sensory / Q000502:physiology*; D005260:Female; D006801:Humans; D008297:Male; D009038:Motion; D004856:Postural Balance / Q000502:physiology*; D011187:Posture / Q000502:physiology*; D013223:Statistics as Topic; D055815:Young Adult
keywords: Center of mass; Center of pressure; Collective variable; Postural control; Virtual time-to-contact; Visual feedback