Impact of accelerometer epoch length on physical activity and sedentary behaviour outcomes for preschool-aged children

Health Rep. 2014 Jan;25(1):3-9.


Background: The Canadian Health Measures Survey uses accelerometry to collect physical activity and sedentary behaviour data. Between cycles 2 and 3, a transition was made from 60-second to 15-second epochs in accelerometry data for children aged 3 to 5. This study examines the impact of epoch length on physical activity and sedentary behaviour outcomes.

Data and methods: Twenty-nine children aged 3 to 5 wore two accelerometers at the same time, one initialized to collect data in 60-second epochs, and the other, in 15-second epochs. Comparisons between epoch settings were made for several physical activity variables.

Results: Compared with the 60-second epoch setting, the 15-second setting captured more moderate-to-vigorous physical activity (MVPA) and sedentary time, but fewer steps and less light and total physical activity. The correlation between epoch settings was high for all variables except steps.

Interpretation: The epoch length used in accelerometer data collection affects physical activity and sedentary behaviour data for preschool-aged children.

Keywords: Ambulation; pediatric; stepping; walking.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Accelerometry*
  • Canada
  • Child
  • Child, Preschool
  • Female
  • Humans
  • Male
  • Motor Activity*
  • Sedentary Behavior*
  • Time Factors