NON CONVENTIONAL METHODS FOR ASSESSING STANDING BALANCE: RELIABILITY EVALUATION OF THE NINTENDO WII BALANCE BOARD

Introduction Standing balance assessment represents a problem in field-based health-related fitness test battery and the research oflow cost, portable and widely available measure toolsis an important issue (Clark et al., 2010; Clark et al., 2011). Therefore, the aim of this study was contributing to analyse the validity and reliability of WII Nintendo Balance Board (WBB) compared with a laboratory-grade force platform (FP) in evaluating subjects balance. The method adopted for comparing WBB and FP was intentionally simple in order to provide a user friendly calibration, in line with the low cost approach to the problem. Method Four unmodified WBB were placed upon theFP and correctly aligned in order to avoid relative rotation of the respective intrinsic coordinate systems. Data from WBB with standard sampling frequency of 30 Hz were treated by an open source software and compared with the set of data obtained by the FP. WBBwere tested in determining the centre of pressure (COP) in different static and dynamic tests. The static test consisted in the evaluation of COP over time for a mass of 64 kg placed on WBB, while dynamic tests involved thirty individuals (17 female, 13 male, age 23.8 •2.7 years). Dynamic tests consisted in double limb standing of 30 s with open and close eyes. Each subject performed 4 trials (2 with opened eyes, 2 with closed eyes). Results In static tests the variation of the COP over time for the WBB with respect to the effective COP position estimated with the FP was limited and similar for all the tools. In dynamic tests it was found a constant offset between COP position on the medio-lateral o anterior-posterior axis that can be related to the effect of horizontal forces on the effective position (Bobbert & Schamhardt, 1990). It was shown that this offset can be easily compensated for each WBB and, after compensation, values of sway path and sway area measures obtained by WBB and FP were comparable. Discussion Frequency sampling of unmodified WBB (30 Hz) is lower than usual frequency sampling of laboratory-grade force platforms (100 Hz) but this does not appear as a limit in evaluating the position of COP over time. Therefore, COP related measures such as sway path and sway area can be estimated in reliable way also by using a low cost set up based on WBB. This can represent a valid and easy-to-use tool for assessing standing balancecontrol. References Clark R, Bryant A, Pua Y, McCroy P, Bennell K, Hunt M (2010).Gait Posture, 31, 307-310. Clark R, McGough R, Paterson K (2011). Gait Posture, 34, 288-291. Bobbert MF, Schamhardt HC (1990). JBiomech, 23, 705-710.