Abstract
[Purpose] The purpose of this study was to investigate the reliability and validity of the kinematic analysis of trunk and pelvis movement during gait and standing as measured by two smartphones (in the present study, we used iPod touches because of their weight). [Methods] Thirty-eight healthy adults (mean age, 21.4 ± 1.2 years) were instructed to stand and walk on a treadmill at three different speeds. The tilt angle of the trunk and pelvis were measured using both an iPod touch and an optoelectronic motion capture system (Optotrak). [Results] The error between the iPod touch and Optotrak was small during standing and walking at low speed. However, as the walking speed was increased, the error between the iPod touch and Optotrak increased. There were no significant differences between the test and retest measurement values of each device, nor were there any significant differences between the days of the analyses. [Conclusions] The iPod touch has good accuracy, since the variations in the test and retest and for different days were small. This suggests that the iPod touch can be used instead of the Optotrak for the kinematic analysis of trunk and pelvis movement at low walking speeds.
