Accuracy Evaluation of Force Measurement Through the Wii Balance Board during Squat and Functional Reach Tests

The Nintendo Wii Balance Board (NWBB) is a commercial low cost device that can be used to measure the force exchanged with the ground and, in such a way, it constitute a valid alternative to expensive laboratory force plates (FP). Because of the lack of horizontal forces measure, the NWBB data resulted affected by inaccuracies when Center of Pressure-(COP) parameters are evaluated. The latter drawback affects in particular dynamic motor tasks, where greater forces are involved. Thus, this paper aimed to compare the NWBB and a FP to assess the error in the vertical force measure in two different highly dynamic tasks such as squatting (SQ) and functional reach test (FR). The findings confirmed the general agreement between the devices when used to measure force and related peaks during SQ and FR test. In particular it appears that the percentage errors are in line with those obtained for COP-parameters when evaluated without horizontal forces from FP, suggesting that this source of inaccuracy is device dependent and does not constitute a limitation of NWBB use in the case of sinale-device study.