Device-independent Physical Activity metrics and adiposity-related indicators among children and adolescents in the United States

This study investigated associations between device-independent physical activity (PA) metrics and adiposity-related indicators among U.S. children and adolescents. Nationally representative cross-sectional data from three NHANES cycles (2011–2014) were analyzed, including 5,274 participants (weighted n = 43,156,858; 49.3% female; ages 6–17 years) who wore accelerometers on their non-dominant wrist for 7 days and had five adiposity-related indicators assessed: BMI z-score, total body and trunk fat percent (DXA), overweight/obesity (BMI), and abdominal obesity (waist-to-height ratio). Raw accelerometry data were used to calculate PA volume (Daily Monitor Independent Movement Summary [MIMS]) and intensity (Peak-60 MIMS). Survey-weighted regression models, adjusted for covariates, showed inverse associations between PA volume (B = −0.230, 95% CI: −0.334,-0.125) and intensity (B = −0.211, 95% CI: −0.250,-0.172) with total body fat percent, trunk fat percent (volume B = −0.192, 95% CI: −0.312,-0.071; intensity B = −0.227, 95% CI: −0.273,-0.181), overweight/obesity (volume OR = 0.967, 95% CI: 0.944,0.991; intensity OR = 0.953, 95% CI: 0.943,0.963) and abdominal obesity (volume OR = 0.963, 95% CI: 0.939,0.988; intensity OR = 0.951, 95% CI: 0.940,0.962). PA intensity was inversely associated with BMI z-score (B = −0.022, 95% CI: −0.028,-0.016). Stronger associations were observed during childhood and among girls. These findings highlight the importance of promoting PA, particularly higher-intensity activities, to mitigate excess adiposity and demonstrate the value of device-independent metrics for PA research.