Abstract
Background
Keywords
Findings
Author
What is already known on this subject?
What does this study add?
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
Findings
The Canadian Health Measures Survey (CHMS) uses accelerometry to directly measure physical activity and sedentary behaviour. Accelerometers record movement data at defined intervals called "epochs." The epoch length used in research ranges from less than one second to one minute. [Full Text]
Author
Rachel C. Colley is with the Health Analysis Division at Statistics Canada and the Children’s Hospital of Eastern Ontario Research Institute, Ottawa, Canada. Alysha Harvey, Kimberly P. Grattan and Kristi B. Adamo are also with the Children’s Hospital of Eastern Ontario Research Institute.
What is already known on this subject?
- The use of accelerometry to measure physical activity among preschool-aged children presents unique challenges because their movement is more sporadic and intermittent than that of older children and adults.
- Research has shown that recording accelerometer data in shorter epochs (intervals) in young children captures more moderate-to-vigorous physical activity, which is a component of the new physical activity guidelines for children aged 0 to 4.
What does this study add?
- A convenience sample of 29 preschool-aged children wore two Actical® accelerometers side-by-side on a belt around their waist for a week.
- Compared with 15-second epoch data, 60-second epoch data recorded less moderate-to-vigorous physical activity and sedentary time, but more daily step counts, light activity and total physical activity.
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