Comparing the performance of three generations of ActiGraph accelerometers

2008; doi:10.1152/japplphysiol.90641.2008.—ActiGraph acceler-ometers are a useful tool for objective assessment of physical activity in clinical and epidemiological studies. Several generations of ActiGraph are being used; however, little work has been done to verify that measurements are consistent across generations. This study employed mechanical oscillations to characterize the dynamic response and intermonitor variability of three generations of ActiGraph monitors, from the oldest 7164 (n 13), 71256 (n 12), to the newest GT1M (n 12). The response due to independent radius (22.1–60.4 mm) and frequency (25–250 rpm) changes were measured, as well as intermonitor variability within each generation. The 7164 and 71256 have similar relationships between activity counts and radius (P 0.229) but were significantly different from the GT1M (P 0.001). The frequency responses were nonlinear in all three generations. Although the response curve shapes were similar, the difference