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Classification Accuracy of a Wearable Activity Tracker for Assessing Sedentary Behavior and Physical Activity in

Wonwoo Byun1, Jung-Min Lee2, Youngwon Kim3,4

  • 1Department of Health, Kinesiology, and Recreation, University of Utah, Salt Lake City, UT 84112, USA. won.byun@utah.edu.

International Journal of Environmental Research and Public Health
|March 29, 2018
PubMed

Insights

The Fitbit activity tracker accurately measures sedentary behavior and total physical activity in preschoolers. However, its accuracy is lower for classifying light and moderate-to-vigorous physical activity intensities.

Area of Science:

  • Pediatric physical activity monitoring
  • Wearable technology in child health
  • Behavioral measurement in early childhood

Background:

  • Accurate quantification of physical activity (PA) and sedentary behavior (SB) is crucial for understanding child health.
  • Preschool-aged children exhibit unique movement patterns that may challenge standard activity monitors.
  • The Fitbit activity tracker (FF) is a popular consumer device, but its validity in young children needs evaluation.

Purpose of the Study:

  • To assess the accuracy of the Fitbit activity tracker (FF) in quantifying sedentary behavior (SB) and different intensities of physical activity (PA) in 3-5-year-old children.
  • To determine the FF's reliability in classifying light physical activity (LPA) and moderate-to-vigorous physical activity (MVPA).
  • To provide evidence for the FF's utility as a measurement tool in preschool populations.

Main Methods:

  • Twenty-eight preschool children (mean age 4.8 years) wore the FF while engaging in free-living activities.
  • Direct observation served as the criterion measure for classifying activity intensity.
  • Statistical analyses included Pearson correlation coefficients (r), mean absolute percent error (MAPE), Cohen's kappa (k), sensitivity (Se), specificity (Sp), and area under the receiver operating curve (ROC-AUC).

Main Results:

  • The FF demonstrated excellent classification accuracy (ROC-AUC) for sedentary behavior (0.92) and total physical activity (0.92).
  • Accuracy was lower for light physical activity (0.63) and moderate-to-vigorous physical activity (0.77).
  • High kappa, Se, Sp, and correct classification percentages were observed for SB and TPA, contrasting with lower values for LPA and MVPA.

Conclusions:

  • The Fitbit activity tracker is a valid instrument for assessing overall physical activity and sedentary time in preschool-aged children.
  • The FF's accuracy is limited in distinguishing between different intensities of physical activity (LPA and MVPA) in this age group.
  • Further research may be needed to refine algorithms or explore alternative methods for accurate PA intensity classification in young children.

Keywords:
accelerometerchildrenobesityphysical activitypreschoolsedentary behavior

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