title: Utilized coefficient of friction during walking: static estimates exceed measured values.
abstract: This study compared utilized coefficient of friction (COF) measured during nonslip pedestrian gait to estimated utilized COF values calculated using anthropometric (i.e., leg length) and stride characteristic data (i.e., impact angle, step length). Twenty healthy adults walked at slow, medium, and fast speeds with kinematic and kinetic data recorded simultaneously. Estimated and measured impact angle varied with walking speed, with greater angles evident with faster speeds (p < 0.001 and p < 0.05, respectively). The estimated impact angle was greater than the measured impact angle (p < 0.05). Estimated and measured peak utilized COF values varied with walking speed, with higher utilized COF values evident with faster speeds (p < 0.001 and p = 0.001, respectively). Estimated utilized COF values were 86, 118, and 131% greater than measured peak utilized COF values for slow, medium, and fast speeds, respectively (p < 0.001). Higher estimated utilized COF values varied moderately with increased measured peak utilized COF values (r = 0.522; p < 0.001). These data suggest that impact angle and step length alone cannot be used to accurately assess the utilized COF on level walking surfaces.
authors.affiliation: Department of Biokinesiology and Physical Therapy, University of Southern California, Los Angeles 90033, USA.
authors.forename: Christopher M
authors.initials: CM
authors.lastname: Powers
authors.forename: Judith M
authors.initials: JM
authors.lastname: Burnfield
authors.forename: Phil
authors.initials: P
authors.lastname: Lim
authors.forename: John M
authors.initials: JM
authors.lastname: Brault
authors.forename: James E
authors.initials: JE
authors.lastname: Flynn
mesh_terms: D000058:Accidental Falls; D000328:Adult; D000886:Anthropometry; D001696:Biomechanical Phenomena; D005260:Female; D017276:Friction; D005684:Gait / Q000502:physiology*; D006801:Humans; D007700:Kinetics; D007866:Leg / Q000502:physiology; D008297:Male; D008433:Mathematics; D012016:Reference Values; D013223:Statistics as Topic / Q000379:methods; D016138:Walking / Q000502:physiology*