Physical activity monitoring in extremely obese adolescents from the teen-LABORATORIES study

Renee M. Jeffreys, Thomas H. Inge, Todd M. Jenkins, Wendy C. King, Vedran Oruc, Andrew D. Douglas, Molly S. Bray

Research output: Contribution to journalArticlepeer-review

2 Scopus citations


Background: The accuracy of physical activity (PA) monitors to discriminate between PA, sedentary behavior, and nonwear in extremely obese (EO) adolescents is unknown. Methods: Twenty-five subjects (9 male/16 female; age = 16.5 ± 2.0 y; BMI = 51 ± 8 kg/m2) wore 3 activity monitors (StepWatch [SAM], Actical [AC], Actiheart [AH]) during a 400-m walk test (400MWT), 2 standardized PA bouts of varying duration, and 1 sedentary bout. Results: For the 400MWT, percent error between observed and monitor-recorded steps was 5.5 ± 7.1% and 82.1 ± 38.6% for the SAM and AC steps, respectively (observed vs. SAM steps: -17.2 ± 22.2 steps; observed vs. AC steps: -264.5 ± 124.8 steps). All activity monitors were able to differentiate between PA and sedentary bouts, but only SAM steps and AH heart rate were significantly different between sedentary behavior and nonwear (P < .001). For all monitors, sedentary behavior was characterized by bouts of zero steps/counts punctuated by intermittent activity steps/counts; nonwear was represented almost exclusively by zero steps/counts. Conclusion: Of all monitors tested, the SAM was most accurate in terms of counting steps and differentiating levels of PA and thus, most appropriate for EO adolescents. The ability to accurately characterize PA intensity in EO adolescents critically depends on activity monitor selection.

Original languageEnglish (US)
Pages (from-to)132-138
Number of pages7
JournalJournal of Physical Activity and Health
Issue number1
StatePublished - Jan 1 2015
Externally publishedYes


  • Obesity
  • Sedentary
  • Validation

ASJC Scopus subject areas

  • Orthopedics and Sports Medicine


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