Average acceleration and intensity gradient of primary school children and associations with indicators of health and well-being

ABSTRACT

Average acceleration (AvAcc) and intensity gradient (IG) have been proposed as standardised metrics describing physical activity (PA) volume and intensity, respectively. We examined hypothesised between-group PA differences in AvAcc and IG, and their associations with health and well-being indicators in children. ActiGraph GT9X wrist accelerometers were worn for 24-h·d⁻¹ over 7days by 145 children aged 9–10. Raw accelerations were averaged per 5-s epoch to represent AvAcc over 24-h. IG represented the relationship between log values for intensity and time. Moderate-to-vigorous PA (MVPA) was estimated using youth cutpoints. BMI z-scores, waist-to-height ratio (WHtR), peak oxygen uptake (VO₂peak), Metabolic Syndrome risk (MetS score), and well-being were assessed cross-sectionally, and 8-weeks later. Hypothesised between-group differences were consistently observed for IG only (p < .001). AvAcc was strongly correlated with MVPA (r = 0.96), while moderate correlations were observed between IG and MVPA (r = 0.50) and AvAcc (r = 0.54). IG was significantly associated with health indicators, independent of AvAcc (p < .001). AvAcc was associated with well-being, independent of IG (p < .05). IG was significantly associated with WHtR (p < .01) and MetS score (p < .05) at 8-weeks follow-up. IG is sensitive as a gauge of PA intensity that is independent of total PA volume, and which relates to important health indicators in children.

KEYWORDS:

• Physical activity
• standardised metrics
• raw accelerations
• GGIR
• wrist
• youth

Acknowledgments

We are grateful to the children and teachers for their participation in the project, and West Lancashire Sport Partnership for their assistance with the data collection. The study was funded by West Lancasire Sport Partnership, West Lancashire Leisure Trust, and Edge Hill University. AVR is with 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. SJF conceived and designed the study, performed the data analyses, and drafted the manuscript. ST contributed to the study design, collected the data, and edited and commented on the manuscript. AVR advised on the data processing and analyses, and edited and commented on the manuscript. LMB advised on the data analyses and edited and commented on the manuscript. RJN contributed to the study design, edited and commented on the manuscript. All authors had final approval of the submitted manuscript.

Data access statement

The data that support the findings of this study are available at https://osf.io/tfpk9/.

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

This work was supported by the Edge Hill University [n/a]; West Lancashire Leisure Trust [n/a]; West Lancashire Sports Partnership [n/a].