Reliability of a Software ImageJ in Motion Measurement: Use of Sit-to-Stand Movements

[Purpose] ImageJ is freeware for image processing, and can measure range of motion. In this study, we examined the reliability of trunk flexion angle evaluation during sit-to-stand movements using ImageJ. [Subjects] Participants were three examinees and ten examiners. [Methods] Markers were attached to the left side of the acromion, great trochanter, and the lateral gap of the knee joint. Sit-to-stand movements of the three examinees were recorded in the saggital plane by a digital video camera. The trunk flexion angle was measured using ImageJ and three dimensional motion analysis was performed. [Results] Intra-rater and inter-rater reliability was analyzed using the intraclass correlation coefficient (ICC) with standard error of measurement (SEM). We confirmed high intra-rater and inter-rater reliability. [Conclusion] We consider that two-dimensional motion analysis using ImageJ is a useful tool for evaluation, study, and education in clinical settings of physical therapy.