title: Do kinematic metrics of walking balance adapt to perturbed optical flow?
abstract: Visual (i.e., optical flow) perturbations can be used to study balance control and balance deficits. However, it remains unclear whether walking balance control adapts to such perturbations over time. Our purpose was to investigate the propensity for visuomotor adaptation in walking balance control using prolonged exposure to optical flow perturbations. Ten subjects (age: 25.4±3.8years) walked on a treadmill while watching a speed-matched virtual hallway with and without continuous mediolateral optical flow perturbations of three different amplitudes. Each of three perturbation trials consisted of 8min of prolonged exposure followed by 1min of unperturbed walking. Using 3D motion capture, we analyzed changes in foot placement kinematics and mediolateral sacrum motion. At their onset, perturbations elicited wider and shorter steps, alluding to a more cautious, general anticipatory balance control strategy. As perturbations continued, foot placement tended toward values seen during unperturbed walking while step width variability and mediolateral sacrum motion concurrently increased. Our findings suggest that subjects progressively shifted from a general anticipatory balance control strategy to a reactive, task-specific strategy using step-to-step adjustments. Prolonged exposure to optical flow perturbations may have clinical utility to reinforce reactive, task-specific balance control through training.
authors.affiliation: Joint Department of Biomedical Engineering, University of North Carolina at Chapel Hill and North Carolina State University, Chapel Hill, NC, USA.
authors.forename: Jessica D
authors.initials: JD
authors.lastname: Thompson
authors.affiliation: Joint Department of Biomedical Engineering, University of North Carolina at Chapel Hill and North Carolina State University, Chapel Hill, NC, USA. Electronic address: jrfranz@email.unc.edu.
authors.forename: Jason R
authors.initials: JR
authors.lastname: Franz
mesh_terms: D000222:Adaptation, Physiological; D000328:Adult; D001696:Biomechanical Phenomena; D005080:Exercise Test; D005260:Female; D005528:Foot / Q000502:physiology; D005684:Gait; D006801:Humans; D021621:Imaging, Three-Dimensional; D035002:Lower Extremity; D008297:Male; D009038:Motion; D004856:Postural Balance; D014785:Vision, Ocular / Q000502:physiology*; D014796:Visual Perception / Q000502:physiology*; D016138:Walking; D055815:Young Adult
keywords: Gait; Sensorimotor; Virtual reality; Vision; Visual feedback