The Accuracy of Pedometer Steps and Time during Walking in Children

PURPOSE: To determine the accuracy of pedometer step counts and time during self-paced walking (SPW) and treadmill walking in children (5-11 yr). Two pedometers were assessed during SPW: Digiwalker SW-200 (DW200) and Walk4Life 2505 (WL), and four pedometers during treadmill walking: DW200, WL, Digiwalker SW-701 (DW701), and the Sun TrekLINQ (SUN). METHODS: Ten boys (8.3+/-1.5 yr) and 10 girls (8.9+/-1.7 yr) completed three single-lap SPW trials around an outdoor athletic track. Treadmill walking was performed at the following speeds: 40, 54, 67, 80, and 94 m.min-1. During treadmill walking, each model was measured on the right and left sides. Pedometer steps and time and observed steps and time were recorded for all trials. RESULTS: Across SPW trials, there was high agreement on observed steps for both the DW200 and WL (intraclass correlation coefficient (ICC) 0.985-0.997). For treadmill walking, at <or=54 m.min-1, low interunit agreement (ICC<or=0.746) and low agreement between pedometer steps and observed steps (ICC<or=0.720) were detected for all models. For pedometer time, the WL exhibited a high level of agreement with observed during SPW (ICC 0.997-0.998). During treadmill walking, the WL was within 5.3% of actual time across all speeds, whereas time with the SUN did not come within 5% agreement until 80 m.min-1. CONCLUSIONS: Findings are consistent with adult studies with step count underestimation during slow (<or=54 m.min-1) walking. Low interunit agreement at slow speeds suggests variations in step count registry within models. The accuracy of time (WL), independent of step count accuracy and speed, suggests that time might be used in addition to steps to quantify the physical activity behavior of children.