Wearable device-measured physical activity and risk of MAFLD in adolescents

While physical activity is known to affect the risk of MAFLD in adults, evidence in adolescents is limited and often based on self-reported questionnaires. We therefore used wearable device-based measurements to investigate the association between physical activity and MAFLD in adolescents.

Data were obtained from the National Health and Nutrition Examination Survey (NHANES) database for adolescents aged 12-19 years during the 2003-2006 and 2011-2014 cycle. Physical activity was measured using wearable accelerometers, averaged across all valid wearing days. Weighted multivariate logistic regressions were applied to assess associations between physical activity (overall, daytime, and nighttime) and MAFLD.

Among 5705 adolescents, higher physical activity levels were strongly associated with lower odds of MAFLD in the 2003-2006 cycle, with a clear dose-response trend across quartiles (P for trend < 0.001). Participants in the highest physical activity (Q4) had 60 % lower odds overall, 58 % lower odds for daytime, and 43 % lower odds for nighttime activity, compared with those with lowest physical activity (Q1). The association between higher physical activity and lower MAFLD risk was generally observed across sex, age, and income subgroups. In contrast, no significant association between physical activity and MAFLD risk was observed in the 2011-2014 cycle.

Our results suggest that higher levels of physical activity, especially during the daytime, may protect against MAFLD in adolescents. Our findings offer partial evidence for the role of circadian activity patterns in MAFLD risk and underscore the need for future studies to validate these associations.