Aim: The purpose of this study was to examine the validity of physical activity by a triaxial accelerometer which was developed in Japan recently. Subjects and Method :Ten healthy young students were studied in this study. They wore a triaxial accelerometer during their daily activities, and their physical activities (lying, sitting, standing, and walking) were videotaped. We examined relationships between the time measured with a triaxial accelerometer and that measured with video camera, and also analyzed the errors between the two measurements by Bland-Altman analysis. Results: The relevance between the two measurements showed a very strong correlation in all measurements. There were no additional errors among supine, standing, and walking but there was additional error in sitting position. There were no proportional errors in all four positions. Conclusion: The validity of physical activity measured by a triaxial accelerometer newly developed was suggested in this study.
