Measuring Children's Physical Activity

Children’s physical activity level was measured with an Actigraph wGT3X accelerometer (Actigraph Corp., Pensacola, FL, United States). Actigraph wGT3X is a lightweight (19 g; 4.6 cm × 3.3 cm × 1.5 cm), triaxial accelerometer, which collects motion data on three orthogonal axes—vertical (Y), horizontal right–left (X), and horizontal front–back axis (Z)—between 0.05 and 2.0 Gs. This accelerometer has been validated for use with children in laboratory and field settings (Santos-Lozano et al., 2012 (link); Delisle et al., 2015 (link); Carson et al., 2019 (link)). Participants wore this equipment using an elastic belt at the waist. The analog acceleration data were converted to a digital signal, and the value (count) was stored in specified time interval (epoch). Ten-second epochs were used for this study. After data collection, the monitor was downloaded to a computer for subsequent data reduction and analysis.