Validation of balance assessment measures of an accelerometric mobile device application versus a balance platform

Abstract

Recent technological advancements in electronics and telecommunications have provided more accessible quantitative methods of assessing balance. The latest smartphones have built-in motion sensors called tri-axial accelerometers, which are an ideal choice for evaluating variability of movement and balance providing a non-invasive, portable method of measurement. PURPOSE: The purpose of this study was to compare the balance assessment measures from a mobile device application (iPod) utilizing accelerometric motion sensors against the balance assessment measures of a clinically valid and reliable balance platform (BIODEX Balance System SD). METHODS: 75 healthy college-aged individuals (37 male, 38 female; average age = 24.2±6.8 yr) performed a series of balance tasks over two visits (Study 1 and Study 2). During Study 1, 8 balance tests were assessed, beginning with two feet on ground (baseline) and progressively becoming more difficult and repeating them over three trials. iPod Touches with a software application to measure balance was used to assess sway. During Study 2, participants completed 4 balance assessments using a clinically validated balance platform and the iPod Touches, at the same time. RESULTS: Data showed that the iPod Touches were consistent with expect outcomes, based off of normative data; the more unstable the assessment the higher the balance score compared to baseline or standing with feet together eyes open without foam. Analyses of the 3 trials suggest that a familiarization test should be performed when using the iPod Touch balance application and this is consistent with other devices. Results from Study 2 showed no significant difference between the two devices when measuring without foam, but a significant difference was found between the two while balancing on foam. CONCLUSION: Balance scores measured by accelerometers within an iPod appear to be a valid and consistent method of measuring human balance.