ASSESSMENT OF PHYSICAL ACTIVITY USING A NEW TRIAXIAL ACCELEROMETER (ACTIVTRACER) IN JAPANESE ADULTS

Abstract

Purpose: We have previously demonstrated the validity of a newly-developed triaxial accelerometer (Activtracer AC300, GMS, Tokyo), compared with oxygen uptake measured using the Douglas bag method, during field walking and jogging (MSSE 32: S327, 1999). Oxygen uptake (ml/kg/min) was predicted as: 5.2 + 0.024 × vector magnitude of acceleration (mG), with R2 = 0.97. In this study, we wanted to assess whether the Activtracer was useful for discriminating among groups of free-living Japanese adults with different activity levels. Methods: Subjects were 63 Japanese adults (46 ± 12 yrs, BMI: 26.1 ± 6.2 kg/m2). They were a convenience sample comprising these groups: 8 diabetics hospitalized for treatment (Gp 1), 20 sedentary adults referred to our outpatient clinic for treatment of various chronic diseases (Gp 2), 21 adults who were being counseled for physical activity at our outpatient clinic using the 1995 ACSM/CDC recommendation (Gp 3), and 14 healthy staff at our hospital (Gp 4). We assumed a priori that Gp 1 and Gp 2 would be more sedentary than Gp 3 and Gp 4. All subjects wore the Activtracer for a day. Using the 5-min average vector magnitude of acceleration, we defined light activities to be those requiring 100–199 mG; moderate, 200–599 mG; and vigorous, ≥ 600 mG. We calculated the average time per day spent on each of these 3 levels of activity and tested for differences among groups using T-test. Results: Table shows that Gp 3 and Gp 4 spent significantly more time in total physical activity than Gp 1 or Gp 2. This difference was primarily due to greater time spent on moderate activities. No differences were observed among groups for light activities, while few subjects spent any time in vigorous activities.TableConclusion: The Activtracer is capable of differentiating, in a free-living setting, among groups of Japanese adults with varying physical activity levels.