title: The intra-rater reliability and agreement of compensatory stepping thresholds of healthy subjects.
abstract: The purpose of this study was to evaluate the test-retest, intra-rater reliability and agreement of compensatory stepping thresholds. A protocol was developed to establish anteroposterior single-stepping thresholds, anteroposterior multiple-stepping thresholds, and lateral single-stepping thresholds. Healthy, young subjects stood on a microprocessor-controlled treadmill, and responded to three series of progressively challenging surface translations. Subjects were instructed to "try not to step" when establishing single-stepping thresholds or "try to take only one step" when establishing multiple-stepping thresholds. Stepping thresholds were defined as the minimum disturbance magnitude that consistently elicited a single or second compensatory step. Thresholds were expressed as the ankle torque necessary to maintain upright posture. Thresholds studied included anterior single-stepping thresholds (τ = 273.0 ± 82.3 N m), posterior single-stepping, thresholds (τ = 235.5 ± 98.0 N m), anterior multiple-stepping thresholds (τ = 977.0 ± 416.3 N m), posterior multiple-stepping thresholds (τ = 701.9 ± 237.5 N m), stability-side lateral single-stepping thresholds (τ = 225.7 ± 77.7 Nm), and mobility-side lateral single-stepping thresholds (τ = 236.8 ± 85.4 N m). Based on intraclass correlation coefficients (ICC) and Bland-Altman plots, all thresholds demonstrated excellent reliability (ICC(2,1) = 0.87-0.97) and agreement. These results suggest that compensatory stepping thresholds have sufficient repeatability to be used in clinical and research-related assessments of fall-risk. Additional study is needed to determine the intra- and inter-rater reliabilities and validity of thresholds specific to the patient populations of interest.
authors.affiliation: Motion Analysis Laboratory, Division of Orthopedic Research, Mayo Clinic, 200 1st Street SW, Charlton North L-110K, Rochester, MN 55905, USA. Electronic address: crenshaw.jeremy@mayo.edu.
authors.forename: Jeremy R
authors.initials: JR
authors.lastname: Crenshaw
authors.affiliation: Motion Analysis Laboratory, Division of Orthopedic Research, Mayo Clinic, 200 1st Street SW, Charlton North L-110K, Rochester, MN 55905, USA. Electronic address: kaufman.kenton@mayo.edu.
authors.forename: Kenton R
authors.initials: KR
authors.lastname: Kaufman
mesh_terms: D061725:Accelerometry / Q000592:standards / Q000706:statistics & numerical data; D000058:Accidental Falls / Q000517:prevention & control; D000328:Adult; D004185:Disability Evaluation; D005080:Exercise Test / Q000592:standards* / Q000706:statistics & numerical data*; D005260:Female; D005684:Gait / Q000502:physiology*; D064368:Healthy Volunteers; D006801:Humans; D008297:Male; D008954:Models, Biological; D015588:Observer Variation; D004856:Postural Balance / Q000502:physiology*; D011187:Posture / Q000502:physiology*; D012016:Reference Values; D015203:Reproducibility of Results; D055815:Young Adult
keywords: Balance; Clinical assessments; Falls; Older adults; Stability