Validity of the Omron pedometer and the actigraph step count function in preschoolers.

Objectives: To validate the GT1M actigraph accelerometer step count function, and the Omron Walking Style Pro pedometer against accelerometer-based activity counts, and to compare pedometer-based and accelerometer-based steps in preschoolers.

Design: A sample of 41 preschoolers (21 boys, mean age 5.43±0.63 years) from one preschool in Flanders, Belgium, was included in data analysis.

Methods: Accelerometer-based and pedometer-based steps were simultaneously collected in this Flemish sample of preschool children. Preschoolers wore two motion sensors (accelerometer and pedometer) for four consecutive days. Pearson correlations were calculated to compare accelerometer activity counts with accelerometer-based steps, accelerometer activity counts with pedometer-based steps and accelerometer-based steps with pedometer-based steps. Bland-Altman analysis was carried out to investigate the agreement between the pedometer-based and the accelerometer-based steps.

Results: Accelerometer-based steps correlated moderately high with accelerometer activity counts per hour (r=0.77) and per day (r=0.82). Pedometer-based steps correlated moderately high with accelerometer activity counts per hour (r=0.65) and per day (r=0.64). High correlations were revealed between steps from both devices (hourly: r=0.92; daily: r=0.89). The Bland-Altman analysis showed a bias of 221.81 (±1679.78) and the limits of agreement ranged from -3070.57 to 3514.18 steps per day.

Conclusions: Both the accelerometer-based as pedometer-based step counts are valid estimates of preschoolers' physical activity levels during free-living activities based on group estimates. High agreement between both step counts justifies combining and comparing pedometer- and accelerometer-based step counts.