title: Strategies for equilibrium maintenance during single leg standing on a wobble board.
abstract: The aim of this study was to identify and compare movement strategies used to maintain balance while single leg standing on either a firm surface (FS) or on a wobble board (WB). In 17 healthy men, retroreflective markers were positioned on the xiphoid process and nondominant lateral malleolus to calculate trunk and contralateral-leg excursion (EXC) and velocity (VEL), and center of pressure (CoP) EXC and VEL during FS on a force platform. From the WB test, standing time (WBTIME) was determined and the board's angular EXC and VEL were calculated from four markers on the WB as surrogate measures for CoP dynamics. Electromyographic average rectified values (ARV) from eight leg and thigh muscles of the supporting limb were calculated for both tasks. WB ARV amplitudes were normalized with respect to the value of FS ARV and presented significantly higher peroneus longus and biceps femoris activity (p<0.05). WB standing time was correlated to trunk sagittal plane velocity (r=-0.73 at p=0.016) and excursion (r=-0.67 at p=0.03). CoP and WB angular movement measures were weakly and not significantly correlated between tasks. This lack of correlation indicates that WB balance maintenance requires movement beyond the ankle strategy as described for the FS task. WB standing likely demands different biomechanical and neuromuscular control strategies, which has immediate implications for the significance of WB tests in contrast to FS balance tests. Differences in control strategies will also have implications for the understanding of mechanisms for rehabilitation training using such devices.
authors.affiliation: Center for Sensory-Motor Interaction (SMI), Department of Health Science and Technology, Aalborg University, Fredrik Bajers Vej 7 D-3, 9220 Aalborg, Denmark(1). Electronic address: pribilva@hst.aau.dk.
authors.forename: Priscila de Brito
authors.initials: Pde B
authors.lastname: Silva
authors.affiliation: Center for Sensory-Motor Interaction (SMI), Department of Health Science and Technology, Aalborg University, Fredrik Bajers Vej 7 D-3, 9220 Aalborg, Denmark(1); Department of Mechanical and Manufacturing Engineering, Aalborg University, Fibigerstraede 16, Aalborg East 9220, Denmark. Electronic address: oliveira@m-tech.aau.dk.
authors.forename: Anderson Souza
authors.initials: AS
authors.lastname: Oliveira
authors.affiliation: Center for Sensory-Motor Interaction (SMI), Department of Health Science and Technology, Aalborg University, Fredrik Bajers Vej 7 D-3, 9220 Aalborg, Denmark(1). Electronic address: nm@hst.aau.dk.
authors.forename: Natalie
authors.initials: N
authors.lastname: Mrachacz-Kersting
authors.affiliation: Center for Sensory-Motor Interaction (SMI), Department of Health Science and Technology, Aalborg University, Fredrik Bajers Vej 7 D-3, 9220 Aalborg, Denmark(1); Physiotherapy Department, University College North Denmark, Selma Lagerløfs Vej 2 - 9220 Aalborg, Denmark(2). Electronic address: ufl@ucn.dk.
authors.forename: Uffe
authors.initials: U
authors.lastname: Laessoe
authors.affiliation: Center for Sensory-Motor Interaction (SMI), Department of Health Science and Technology, Aalborg University, Fredrik Bajers Vej 7 D-3, 9220 Aalborg, Denmark(1). Electronic address: uwek@hst.aau.dk.
authors.forename: Uwe Gustav
authors.initials: UG
authors.lastname: Kersting
mesh_terms: D000328:Adult; D004576:Electromyography; D006801:Humans; D007866:Leg / Q000502:physiology*; D008297:Male; D009068:Movement / Q000502:physiology*; D018482:Muscle, Skeletal / Q000502:physiology; D004856:Postural Balance / Q000502:physiology*
keywords: Ankle disc; Balance; Balance board; Injury prevention; Motor control