The use of the intensity gradient and average acceleration metrics to explore associations with BMI z-score in children

Citation

Buchan DS, McLellan G, Donnelly S & Arthur R (2019) The use of the intensity gradient and average acceleration metrics to explore associations with BMI z-score in children. Journal of Sports Sciences, 37 (23), pp. 2751-2758. https://doi.org/10.1080/02640414.2019.1664536

Abstract
This study used the intensity gradient (IG) and average acceleration metrics to describe children’s activity profiles and explore associations with body mass index (BMI) z-score. Two hundred and forty-six children (n = 138 girls) aged 9.6 ± 1.4 years wore a wrist-mounted ActiGraph wGT3X-BT accelerometer for 7 days on their non-dominant wrist. Physical activity (PA) metrics captured included: the IG which describes the intensity distribution of accelerations across the 24 h monitoring period; average acceleration which provides a measure of the volume of activity; total moderate-to-vigorous PA (MVPA) and inactive time. Acceleration was averaged over 5s epochs. Finally, BMI z-score was calculated for each participant. Average acceleration was negatively associated with BMI z-score (p < 0.05) independent of age and gender but not IG. The IG was negatively associated with BMI z-score independent of potential correlates and average acceleration. Total MVPA was not associated with BMI-z score. The IG and average acceleration metrics may be used to explore the independent or cumulative effects of the volume and intensity distribution of activity upon measures of health and well-being in children to inform specific activity recommendations.

Keywords
ActiGraph; accelerometer; activity metrics; wrist-worn; raw acceleration

Journal
Journal of Sports Sciences: Volume 37, Issue 23