Device-Agnostic Physical Activity Metrics and Adiposity-Related Indicators Among Children and Adolescents in the United States

Purpose: This study investigated associations between device-agnostic physical activity (PA) volume and intensity metrics/outcomes in relation to adiposity-related indicators among children and adolescents. Methods: Nationally representative cross-sectional data from three cycles of the U.S. National Health and Nutrition Survey (2011-2012; 2012 National Youth Fitness Survey; 2013-2014) were analyzed. A total of 5 260 participants (weighted n = 43 156 858; 49% female; ages 6-17 years) wore an accelerometer on their non-dominant wrist for 7-days. Monitor Independent Movement Summary (MIMS) units were extracted from raw accelerometry data to calculate PA volume (Daily MIMS) and intensity (Peak 60-min MIMS). Four adiposity-related indicators were examined: body mass index (BMI) z-score, total body fat percent via dual-energy X-ray absorptiometry, overweight/obesity status (via BMI), and abdominal obesity status (via waist-to-height ratio classification). Survey-weighted linear and logistic regression models were computed, adjusted for covariates. Results: PA volume and intensity were inversely associated with significantly lower BMI z-score and total body fat percent, and odds of being classified as having overweight/obesity and abdominal obesity. Moderation analyses revealed the relationships between both PA metrics and total body fat percent were stronger during childhood (than adolescence) and among girls, but not for the other anthropometric-derived adiposity indicators. Conclusions: These findings further support the importance of promoting physical activity participation – especially activities of higher intensity – to combat excess adiposity, while also pointing to who (girls) these associations are strongest for and when (during childhood). Moving forward, researchers are encouraged to adopt device-agnostic PA metrics to facilitate harmonized data analysis as we seek more precise estimates to better inform public health recommendations surrounding excess adiposity prevention and management.