title: Corner height influences center of mass kinematics and path trajectory during turning.
abstract: Despite the prevalence of directional changes during every-day gait, relatively little is known about turning compared to straight gait. While the center of mass (COM) movement during straight gait is well characterized, the COM trajectory and the factors that influence it are less established for turning. This study investigated the influence of a corner׳s height on the COM trajectory as participants walked around the corner. Ten participants (25.3±3.74 years) performed both 90° step and spin turns to the left at self-selected slow, normal, and fast speeds while walking inside a marked path. A pylon was placed on the inside corner of the path. Four different pylon heights were used to correspond to heights of everyday objects: 0 cm (no object), 63 cm (box, crate), 104 cm (desk, table, counter), 167 cm (shelf, cabinet). Obstacle height was found to significantly affect the COM trajectory. Taller obstacles resulted in more distance between the corner and the COM, and between the corner and the COP. Taller obstacles also were associated with greater curvature in the COM trajectory, indicating a smaller turning radius despite the constant 90° corner. Taller obstacles correlated to an increased required coefficient of friction (RCOF) due to the smaller turning radii. Taller obstacles also tended towards greater mediolateral (ML) COM-COP angles, contrary to the initial hypothesis. Additionally, the COM was found to remain outside the base of support (BOS) for the entire first half of stance phase for all conditions indicating a high risk of falls resulting from slips.
authors.affiliation: Department of Mechanical Engineering, Virginia Polytechnic Institute and State University, Blacksburg, Virginia.
authors.forename: Peter C
authors.initials: PC
authors.lastname: Fino
authors.affiliation: School of Biological and Health Systems Engineering, Ira A. Fulton Schools of Engineering, Arizona State University, Tempe, Arizona. Electronic address: thurmon.lockhart@asu.edu.
authors.forename: Thurmon E
authors.initials: TE
authors.lastname: Lockhart
authors.affiliation: Department of Biostatistical Sciences, Division of Public Health Sciences, Wake Forest School of Medicine, Winston-Salem, North Carolina.
authors.forename: Nora F
authors.initials: NF
authors.lastname: Fino
mesh_terms: D000293:Adolescent; D000328:Adult; D001696:Biomechanical Phenomena; D005260:Female; D017276:Friction; D005684:Gait; D006801:Humans; D008297:Male; D008875:Middle Aged; D009068:Movement; D016138:Walking / Q000502:physiology*; D055815:Young Adult
keywords: Biomechanics; COM; Center of mass; Gait; RCOF; Speed; Turning; Turning angle