The intra-rater reliability and agreement of compensatory stepping thresholds of healthy subjects

• Published in: Gait & posture Vol. 39; no. 2; pp. 810 - 815
• Main Authors: Crenshaw, Jeremy R., Kaufman, Kenton R.
• Format: Journal Article
• Language: English
• Published: England Elsevier B.V 01.02.2014
• Subjects: Accelerometry - standards; Accelerometry - statistics & numerical data; Accidental Falls - prevention & control; Adult; Balance; Clinical assessments; Disability Evaluation; Exercise Test - standards; Exercise Test - statistics & numerical data; Falls; Female; Gait - physiology; Healthy Volunteers; Humans; Male; Models, Biological; Observer Variation; Older adults; Orthopedics; Postural Balance - physiology; Posture - physiology; Reference Values; Reproducibility of Results; Stability; Young Adult; Falls; Clinical assessments; Stability; Balance; Older adults
• ISSN: 0966-6362; 1879-2219; 1879-2219
• DOI: 10.1016/j.gaitpost.2013.11.006

•Young adults responded to three progressive series of treadmill accelerations.•Subjects were instructed to either try “not to step” or “to take only one step”.•Anteroposterior single-stepping and multiple-stepping thresholds were identified.•Lateral single-stepping thresholds were identified.•Thresholds demonstrated excellent intrarater reliability (ICC (2,1)=0.87–0.97). 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±82.3Nm), posterior single-stepping, thresholds (τ=235.5±98.0Nm), anterior multiple-stepping thresholds (τ=977.0±416.3Nm), posterior multiple-stepping thresholds (τ=701.9±237.5Nm), stability-side lateral single-stepping thresholds (τ=225.7±77.7Nm), and mobility-side lateral single-stepping thresholds (τ=236.8± 85.4Nm). 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.