Test-retest reliability of force plate-derived measures of reactive stepping

Abstract

Background: Characterizing reactive stepping is important to describe the response's effectiveness. Measures of reactive stepping related to step initiation, execution, and termination phases have been frequently reported to characterize reactive balance control. However, the testretest reliability of these measures are unknown. Research questions: What is the between-and within-session test-retest reliability of various force plate-derived measures of reactive stepping? Methods: Nineteen young, healthy adults responded to 6 small (~8-10% of body weight) and 6 large perturbations (~13-15% of body weight) using an anterior lean-and-release system. Tests were conducted on two visits separated by at least two days. Participants were instructed to recover balance in as few steps as possible.Step onset, foot-off, swing, and restabilization times were extracted from force plates. Relative test-retest reliability was determined through intraclass correlation coefficients (ICCs) and 95% confidence intervals (CIs). Absolute test-retest reliability was assessed using the standard error of the measurement (SEM). Results: Foot-off and swing times had the highest between-and within-session test-retest reliabilities regardless of perturbation size (between-session ICC=0.898-0.942; within-session ICC=0.455-0.753). Conversely, step onset and restabilization time had lower ICCs and wider CIs (between-session ICC=0.495-0.825; within-session ICC=-0.040-0.174). Between-session testretest reliability was higher (ICC=0.495-0.942) for all measures than within-session test-retest reliability (ICC=-0.040-0.753). SEMs were low (3-10% of mean) for all measures, except time to restabilization (SEM=15-20% of mean), indicating good absolute reliability. Significance: These findings suggest multiple baseline sessions are needed for measuring restabilization and step onset times. The SEMs provide an index for measuring meaningful change due to an intervention.

Spatial Characteristics Of Reactive Stepping Among People Living With Chronic Incomplete Spinal Cord Injury

“…The results of this study found good to excellent test-retest reliability for foot-off (start of reactive step) and swing time of the reactive step using the lean-and-release test (Saumur et al, 2021). Additionally, all of the temporal measures demonstrated good absolute reliability other than time to restabilization (Saumur et al, 2021). However, a measurement's degree of reliability for one particular group may not translate to another group with unique characteristics (Roach, 2006).…”

“…Recently, a study by Saumur et al (2021), examining the test-retest reliability of the temporal measures of reactive stepping during the Lean-and-Release test, was conducted on a group of healthy adults. The results of this study found good to excellent test-retest reliability for foot-off (start of reactive step) and swing time of the reactive step using the lean-and-release test (Saumur et al, 2021). Additionally, all of the temporal measures demonstrated good absolute reliability other than time to restabilization (Saumur et al, 2021).…”

The effect of perturbation magnitude on lower limb muscle activity during reactive stepping using functional data analysis

“…Nineteen participants took part in this study (27.6 (3.0) years; 9 men and 10 women) (Saumur et al, 2020). A summary of the number of trials used for analysis for each muscle can be found in Table 1.…”

“…Participants in this study have been described in detail previously (Saumur et al, 2020) where they participated in a test-retest reliability study. EMG was recorded during the first session and used in the present study.…”

“…Perturbation onset was defined as < 5 N of force on the load cell, and foot contact occurred when the stepping force plate ground reaction forces exceeded 5 N (Saumur et al, 2020). Foot-off time was determined as the time when the mediolateral centre of pressure was 20% of the maximum slope when shifting towards the stepping limb (Kurz et al, 2013;Saumur et al, 2020). Trials were excluded if participants took more than one step to respond to the perturbation.…”