Accelerometer epoch length influence associations for physical activity intensities with body mass index and locomotor skills in young children

ABSTRACT

The epoch length is decisive for the capture of physical activity intensities from accelerometry and possibly for associations between physical activity intensities and outcomes in children. The aim of the present study was to determine the multivariate physical activity intensity signatures related to body mass index and locomotor skills in preschool children using different epoch lengths. A sample of 1054 Norwegian children (mean age 4.8 years, 52% boys) from the Sogn og Fjordane Preschool Physical Activity Study provided data on physical activity (ActiGraph GT3X+), body mass index and locomotor skills in 2015–2016. Multivariate pattern analysis was used to determine associations between the physical activity intensity spectrum (0–99 to ≥15000 counts per minute) and the outcomes using files aggregated using 8 different epoch lengths from 1 to 60 seconds. We observed that associations across the intensity spectrum, from sedentary time to vigorous intensities, differed for data derived using different epoch lengths. For both outcomes, associations for moderate intensities became stronger and vigorous intensities became weaker for longer as compared to shorter epoch lengths. Aggregation of accelerometer data using different epoch lengths influences the capture of physical activity intensities and associations between physical activity intensities and related outcomes.

KEYWORDS:

• Multivariate pattern analysis
• paediatric
• childhood
• accelerometer
• intensity

Acknowledgments

We thank all children, parents and staff at the participating preschools for their participation in the study and their excellent cooperation during the data collection. We also thank colleagues and students at the Western Norway University of Applied Sciences (formerly Sogn og Fjordane University College) for their contribution to the study. The study was funded by the Sogn og Fjordane County Municipality and Sogn og Fjordane University College.

Disclosure statement

No potential conflict of interest was reported by the authors.

Data availability statement

The datasets used in the current study are available from the corresponding author on reasonable request.

Additional information

Funding

The study was funded by the Sogn og Fjordane County Municipality and Sogn og Fjordane University College [NA].