Influence of Guideline Operationalization on Youth Activity Prevalence in the International Children's Accelerometry Database.

Abstract

INTRODUCTION: The United Kingdom and World Health Organization recently changed their youth physical activity (PA) guidelines from 60 minutes of moderate-vigorous PA (MVPA) every day, to an average of 60 minutes of MVPA per day, over a week. The changes are based on expert opinion due to insufficient evidence comparing health outcomes associated with different guideline definitions. This study used the International Children's Accelerometry Database to compare approaches to calculating youth PA compliance and associations with health indicators. METHODS: Cross-sectional accelerometer data (n = 21,612, 5-18y) was used to examine compliance with four guideline definitions: daily method (DM; ≥60 minutes MVPA every day), average method (AM; average of ≥60 minutes MVPA per day), AM5 (AM compliance and ≥ five minutes of vigorous PA [VPA] on ≥three days), AM15 (AM compliance and ≥ 15 minutes VPA on ≥three days). Associations between compliance and health indicators were examined for all definitions. RESULTS: Compliance varied from 5·3% (DM) to 29·9% (AM). Associations between compliance and health indicators were similar for AM, AM5, and AM15. For example, compliance with AM, AM5, and AM15 was associated with a lower BMI z-score (statistics are coefficient [95%CI]): AM (-0.28[-0.33,-0.23]), AM5 (-0.28[-0.33,-0.23], AM15 (-0.30[-0.35,-0.25]). Associations between compliance and health indicators for DM were similar/weaker, possibly reflecting fewer DM-compliant participants with health data and lower variability in exposure/outcome data. CONCLUSIONS: Youth completing 60 minutes of MVPA every day do not experience superior health benefits to youth completing an average of 60 minutes of MVPA per day. Guidelines should encourage youth to achieve an average of 60 minutes of MVPA per day. Different guideline definitions impact inactivity prevalence estimates; this must be considered when analyzing data and comparing studies.