title: Stance time and step width variability have unique contributing impairments in older persons.
abstract: Gait variability may have multiple causes. We hypothesized that central nervous system (CNS) impairments would affect motor control and be manifested as increased stance time and step length variability, while sensory impairments would affect balance and be manifested as increased step width variability. Older adults (mean+/-standard deviation (S.D.) age=79.4+/-4.1, n=558) from the Pittsburgh site of the Cardiovascular Health Study participated. The S.D. across steps was the indicator of gait variability, determined for three gait measures, step length, stance time and step width, using a computerized walkway. Impairment measures included CNS function (modified mini-mental state examination, Trails A and B, Digit Symbol Substitution, finger tapping), sensory function (lower extremity (LE) vibration, vision), strength (grip strength, repeated chair stands), mood, and LE pain. Linear regression models were fit for the three gait variability characteristics using impairment measures as independent variables, adjusted for age, race, gender, and height. Analyses were repeated stratified by gait speed. All measures of CNS impairment were directly related to stance time variability (p<0.01), with increased CNS impairment associated with increased stance time variability. CNS impairments were not related to step length or width variability. Both sensory impairments were inversely related to step width (p<0.01) but not step length or stance time variability. CNS impairments affected stance time variability especially in slow walkers while sensory impairments affected step width variability in fast walkers. Specific patterns of gait variability may imply different underlying causes. Types of gait variability should be specified. Interventions may be targeted at specific types of gait variability.
authors.affiliation: Department of Physical Therapy, School of Health and Rehabilitation Sciences, University of Pittsburgh, Pittsburgh, PA 15260, United States. jbrach@pitt.edu
authors.forename: Jennifer S
authors.initials: JS
authors.lastname: Brach
authors.forename: Stephanie
authors.initials: S
authors.lastname: Studenski
authors.forename: Subashan
authors.initials: S
authors.lastname: Perera
authors.forename: Jessie M
authors.initials: JM
authors.lastname: VanSwearingen
authors.forename: Anne B
authors.initials: AB
authors.lastname: Newman
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D001696:Biomechanical Phenomena; D005260:Female; D020233:Gait Disorders, Neurologic / Q000503:physiopathology*; D006801:Humans; D016014:Linear Models; D008137:Longitudinal Studies; D008297:Male; D009483:Neuropsychological Tests; D004856:Postural Balance / Q000502:physiology; D016059:Range of Motion, Articular; D012307:Risk Factors; D012815:Signal Processing, Computer-Assisted