Reliability of static standing balance in nondisabled children: Comparison of two methods of measurement

Abstract

Static standing balance is commonly measured with research laboratory systems (LabSys) or clinical systems (ClinSys). The purposes of this study were to (1) assess the reliability of two systems designed to measure static standing balance in nondisabled children, (2) compare the findings derived from the two systems of measurement, and (3) examine the relationship between anthropometric measures and postural sway. Twenty-five nondisabled children (12 male, 13 female) ages 1 year 11 months to 12 years 2 months (mean = 6 years 4 months; SD = 4 years 3 months) participated in the study. Each child stood on the LabSys and the ClinSys for three consecutive 10 second measurement periods. Intraclass correlation coefficients (ICC (2, 1)) for the three trials on each system were 0.62 (LabSys) and 0.63 (ClinSys). The level of agreement between the two systems was 0.61 (ICC (2, 1)). Younger children exhibited more variability and less agreement between measurement trials using the ClinSys. However, older children demonstrated more similar sway indices when comparing the two systems of measurement. Two-way analysis of variance indicated that there were significant differences between sway indices measured by the two systems (p < 0.01) and between the youngest children (aged 2–4 years) and all other children (p < 0.01). In addition, agreement among trials for the two systems was different depending on the age group measured. Correlation coefficients for sway index and age, height, weight, and foot length ranged from -0.52 to -0.64 for the LabSys (p < 0.01) and -0.62 to -0.73 for the Clin-Sys (p < 0.01). Stepwise multiple regression analysis indicated that height was the most significant predictor of sway when measured by the ClinSys (R² = 0.536, p < 0.01) whereas age was the most significant predictor when sway was measured using the LabSys (R² = 0.403, p < 0.01). The results suggest that the degree of postural sway and the reliability of the measurement itself are influenced by the age of the child and the measurement system employed.

Key Words:

• stance
• development
• postural sway
• postural stability
• balance