ABSTRACT
The use of high-resolution physical activity intensity spectra obtained from accelerometry can improve knowledge of associations with health and development beyond the use of traditional summary measures of intensity. The aim of the present study was to compare three different approaches for determining associations for spectrum descriptors of physical activity (the intensity gradient, principal component analysis, and multivariate pattern analysis) with relevant outcomes in children. We used two datasets including physical activity spectrum data (ActiGraph GT3X+) and 1) a cardiometabolic health outcome in 841 schoolchildren and 2) a motor skill outcome in 1081 preschool children. We compared variance explained (R2) and associations with the outcomes for the intensity gradient (slope) across the physical activity spectra, a two-component principal component model describing the physical activity variables, and multivariate pattern analysis using the intensity spectra as the explanatory data matrices. Results were broadly similar for all analytical approaches. Multivariate pattern analysis explained the most variance in both datasets, likely resulting from use of more of the information available from the intensity spectra. Yet, volume and intensity dimensions of physical activity are not easily disentangled and their relative importance may be interpreted differently using different methodology.
Acknowledgments
We thank all children, parents and staff at the participating preschools (PRESPAS) and schools (ASK) for 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 ASK and PRESPAS studies. AR is supported by the NIHR Leicester Biomedical Research Centre, and the Collaboration for leadership in Applied Health Research and Care (CLAHRC) East Midlands. The views expressed are those of the authors and not necessarily those of the NHS, NIHR, or Department of Health.
Authors’ contributions
EAA developed the idea of the study. EAA and AKON collected the data. EAA and OMK designed the study and analyzed the data. EAA wrote the manuscript draft. All authors discussed the interpretation of the results, and read and approved the final manuscript.
Data availability statement
The datasets used in the current study are available from the corresponding author on reasonable request.
Disclosure of interests
The authors declare that they have no competing interests.
Supplementary material
Supplemental data for this article can be accessed here.