Reliability and criterion validity of the "Gyroscope" application of the iPod™ for measuring lumbar range of motion.

Abstract

Recent technologies, such as the iPod, are often equipped with an accelerometer and magnetometer, which, through software applications, can perform various inclinometric functions. These applications have the potential to measure and quantify range of motion (ROM). The purpose of this study was to estimate the iPod "Gyroscope" application intra- and inter-rater reliability as well as its criterion validity in healthy participants lumbar ROM assessment. The sample consisted of 29 healthy participants. For the estimation of intra- and inter-reliability, two examiners measured the lumbar ROM of each participant twice using the iPod. To estimate the criterion validity, the measures were compared to those obtained with the Back Range of Motion Device (BROM; lateral flexion) and the double inclinometer (flexion and extension). Reliability and validity were then established using the intraclass correlation coefficient (ICC). We observed a moderate to high intra-rater reliability (ICCs = 0.67-0.91) and a moderate to high inter-rater reliability for each movement (ICCs = 0.72-0.89). For the criterion validity, the ICCs were all high (ICCs = 0.65-0.89). Our results provide evidence that the iPod "Gyroscope" application can be used to assess lumbar ROM for all movements.