The Accuracy of the Accelerometers (Actical and Actigraph) among Korean People

ABSTRACT

BACKGROUND: Nowadays, decreased physical activity is considered to be a contributor to increase the prevalence of many diseases such as obesity, coronary heart disease and so on. Many researches demonstrated that regular physical activity reduce all cause mortality. To increase the physical activities of the population, accurate estimation of the activities is needed. Actical and actigraph are confirmed as accurate tools to measure physical activities. But the target populations of the validity studies were not Asian people. Therefore, the accuracy of the accelerometers should be confirmed in Asian people. The accuracy of the tools could be different. Therefore head to head comparison study between the tools would be needed. METHODS: Thirty volunteers from the community, ages over 20 yrs, were recruited. The participants put on the two accelerometers (Actical, Actigraph) on the waists, secured with elastic belts, and performed a session of rest and three structured activities (two walking speeds, 4 km/hr and 6 km/hr, and one jogging speed, 8 km/hr). During each activity, expired respiratory gases were collected, and oxygen consumption (VO2) was measured by indirect calorimetry (Model Quark beta2(R)). The calories measured by gas analyzer and two accelerometers were compared by correlation analysis using SPSS program. RESULTS: Pearson correlation coefficient between gas analyzer and two accelerometers was calculated at three structured activities. The r in Actical was 0.747, 0.785, and 0.677, at speed of 4, 6, 8 km/hr, respectively (P<0.05), and the same measures in Actigraph was 0.617, 0.737, and 0.530 (P<0.05), respectively. Pearson correlation coefficient was also calculated between the two accelerometers, and the r was 0.881, 0.927, and 0.824, at each speed. CONCLUSION: The Actical and Actigraph are valid tools for measuring physical activities in Korean people.