Estimating Physical Activity in Children: Impact of Pedometer Wear Time and Metric

in Journal of Physical Activity and Health
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The purpose of this study was to provide a practical demonstration of the impact of monitoring frame and metric when assessing pedometer-determined physical activity (PA) in youth.


Children (N = 1111) were asked to wear pedometers over a 7-day period during which time worn and steps were recorded each day. Varying data-exclusion criteria were used to demonstrate changes in estimates of PA. Steps were expressed using several metrics and criteria, and construct validity was demonstrated via correlations with adiposity.


Meaningful fluctuations in average steps per day and percentage meeting PA recommendations were apparent when different criteria were used. Children who wore the pedometer longer appeared more active, with each minute the pedometer was worn each day accounting for an approximate increase of 11 and 8 steps for boys and girls, respectively (P < .05). Using more restrictive exclusion criteria led to stronger correlations between indices of steps per day, steps per minute, steps per leg length, steps per minute per leg length, and obesity.


Wear time has a meaningful impact on estimates of PA. This should be considered when determining exclusion criteria and making comparisons between studies. Results also suggest that incorporating wear time per day and leg length into the metric may increase validity of PA estimates.

Laurson ( is with the School of Kinesiology and Recreation, Illinois State University, Normal, IL. Welk is with the Dept of Health and Human Performance, Iowa State University, Ames, IA. Eisenmann is with the Dept of Radiology, Michigan State University, East Lansing, MI.