Validity of a Smartphone-based instrumented Timed Up and Go

The Timed Up and Go (TUG) is one of the most widely used clinical tests to assess balance and mobility. An instrumented Timed Up and Go (iTUG) makes use of a specialized measurement system (e.g. an accelerometer) to identify and evaluate specific mobility skills. Nowadays a Smartphone (SP) comes with a large set of embedded sensors, including an accelerometer. An SP is a user-friendly device able to perform ubiquitous sensing with a variety of connectivity options. In this study we evaluate the validity of an SP for instrumenting the TUG. We examined 49 subjects (59 16 years old), without defining any inclusion criteria, using both an SP and a McRoberts Dynaport Hybrid, a device specifically designed for movement analysis. The statistical agreement between the two measurement systems is good for some of the parameters described in literature, which are of clear clinical value. Inter-rater reliability is often excellent and intra-rater reliability has been assessed in a subgroup of 25 subjects finding the same results for the two devices. In conclusion we found evidence that the SP is capable of becoming a pervasive and low-cost tool for the quantitative analysis of balance and mobility. (C) 2012 Elsevier B.V. All rights reserved.