Examining Changes to Center of Pressure during the First Trials of Wii Gameplay

Objective: Use of the Nintendo Wii as a balance assessment and rehabilitation tool continues to grow. One advantage of the Wii is that games can serve as a virtual reality training tool; however, a disadvantage of the Wii is the human-machine interface and the learning effect over multiple trials. The purpose of this study was to assess changes in postural control during Wii gameplay over a series of trials in novice players. Materials and Methods: Thirty-one university athletes (aged 18-25 years) completed four trials of the Nintendo Wii Fit soccer heading (SH) balance game. Center of pressure (COP) was calculated in the anterior-posterior (AP) and medial-lateral (ML) directions for each 70-second time trial at 1000 Hz. COP was assessed using six linear and two nonlinear measures. Repeated measures analysis of variances compared COP measures over the four trials. Results: Significant differences in COP magnitude and velocity were found between trials 1 and 2 in the ML direction. No significant effects of trial were found in the AP direction. In contrast, a measure of the overall area of COP using an ellipse method revealed a significant reduction to COP area between trials 3 and 4. No significant differences between trials were observed in nonlinear measures. Conclusions: These results demonstrate how magnitude and velocity measures of COP control stabilize after the first trial of Wii SH game play in novice young adults. As Wii rehabilitation focuses on individuals with balance difficulties, an important consideration when using the game as an assessment tool is that more than four trials may be required to capture learning in these populations. In addition, contrasting results from ellipse measurement methods point to the use of multiple measures for robust description of COP behavior. This work provides understanding of normative postural control responses with further research in clinical populations needed