Reliability of the Wii Balance Board for measurement of steady state balance in children aged 6-9 years.

Purpose: The Wii Balance Board (WBB) can be used for assessment of steady state balance (SSB), but its reliability has not been studied in children aged 6-9 years. This study aimed to determine the test-retest reliability of the WBB for measuring SSB in this population. A secondary aim was to determine the minimum detectable change (MDC) and standard error of measurement (SEM) of the WBB in children aged 6-9 years.

Methods: 52 children between 6-9 years of age participated. "One leg stand balance" was used to assess center of pressure velocity (COPV) and center of pressure area (COPA) on three occasions by the same tester. Two tests were conducted on the same day (Day 1) and the third test was performed on another day (Day 2), with a period of 5-13 days between the two test days. Intraclass correlation coefficient (ICC 3,1), SEMs, and MDC were calculated.

Results: Intra-day test-retest reliability of COPA was found to be good (ICC3,1 =0.86; 95% confidence interval [CI]: 0.75, 0.92) and that of COPV was also found to be good (ICC3,1 =0.87; 95% CI: 0.77, 0.92). Inter-day test-retest reliability was found to be good for COPA (ICC3,1 = 0.87; 95% CI: 0.75, 0.93) and COPV (ICC3,1 = 0.89; 95% CI: 0.81, 0.94). SEM for COPA in intra-day testing was 18.90 mm2 (15.78%), and in inter-day testing it was 16.44 mm2 (13.61%). SEM for COPV in intra-day testing was 1.12 mm/s (7.6%), and in inter-day testing it was 1.01 mm/s (6.9%). MDC for COPA in intra-day testing was 52.41mm2 (42.75%), and in inter-day testing was 45.58 mm2 (35.75%). MDC for COPV in intra-day testing was 3.11 mm/s (21.2%), and in inter-day testing it was 2.80 mm/s (18.9%).

Conclusion: The WBB has good test-retest reliability for assessing SSB of children between 6-9 years. COPA measurements appear to be less sensitive to clinical changes in SSB when compared to COPV. Assessment of validity of the WBB in this age group is recommended before it can be considered as a potential balance assessment tool in children.