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Agreement of objectively measured physical activity and sedentary time in preschool children
Eivind Aadland1, Kjersti Johannessen1
1Faculty of Teacher Education and Sport, Sogn og Fjordane University College, Box 133, 6851 Sogndal, Norway.
Insights
Preschoolers show considerable week-to-week variability in objectively measured physical activity and sedentary behavior. Researchers must account for this intra-individual variability in accelerometer data for accurate epidemiological findings.
Area of Science:
- Pediatric epidemiology
- Physical activity and sedentary behavior research
- Childhood obesity prevention
Background:
- Objective measurement of physical activity (PA) and sedentary behavior (SED) is crucial in preschool children.
- Understanding the reliability of these measurements over short periods is essential for accurate research.
Purpose of the Study:
- To assess the intra-individual agreement of objectively measured PA and SED over two consecutive weeks in preschool children.
- To evaluate the reliability of accelerometer data using various wear time criteria.
Main Methods:
- Ninety-one preschool children (3-5 years) wore accelerometers for 14 consecutive days.
- Week-by-week reliability was analyzed using intraclass correlation (ICC) and Bland-Altman plots.
- Different wear time criteria (e.g., ≥ 8 hours/day, ≥ 3 days/week) were applied.
Main Results:
- High week-by-week ICC (≥ 0.75) was observed for most PA and SED variables.
- Absolute sedentary time showed lower ICC (0.61-0.81).
- Limits of agreement indicated substantial intra-individual variability, equivalent to 1.0-1.6 standard deviation units.
Conclusions:
- Significant week-by-week variability exists in accelerometer-measured PA and SED in preschool children.
- Researchers must acknowledge and address this intra-individual variability to ensure valid epidemiological conclusions.
- Awareness of measurement noise is critical for interpreting research findings in this age group.
Objective:
To determine the intra-individual agreement for objectively measured physical activity (PA) and sedentary behavior (SED) over two subsequent weeks in preschool children.
Method:
Ninety-one children aged 3 to 5 years (49% boys) from three preschools in Sogn og Fjordane, Norway, provided 14 consecutive days of accelerometer data (Actigraph GT3X +) during the autumn of 2014. Week-by-week reliability was assessed using intraclass correlation (ICC), Bland-Altman plots and 95% limits of agreement for different wear time criteria (≥ 6, 8 and 10 h/day and ≥ 3 and 5 days/week).
Results:
The week-by-week ICC was ≥ 0.75 for all variables across all wear criteria applied, except for absolute sedentary time (ICC 0.61-0.81). Using a ≥ 8 h/day and ≥ 3 days/week criterion (n = 78), limits of agreement were ± 209.5 cpm for overall PA, ± 68.6 min/day for SED, ± 43.8 min/day for light PA, ± 20.2 min/day for moderate-to-vigorous PA, and ± 55.9 min/day for light-to-vigorous PA, equaling 1.0-1.6 standard deviation units.
Conclusion:
Considerable week-by-week variability was found for all variables. Researchers need to be aware of substantial intra-individual variability in accelerometer-measurements and take necessary actions according to the hypothesis under study, as noise in any measurement will preclude researchers' ability to arrive at valid conclusions in epidemiology.
