Longitudinal associations between adherence to 24-h movement guidelines and physical fitness and body composition in pediatric overweight and obesity

This study investigated the longitudinal associations between adherence to the 24-h Movement Guidelines (24-HMG), specifically, meeting the recommendations for moderate-to-vigorous physical activity (MVPA) (≥ 60 min/day), recreational screen time (≤ 2 h/day), and sleep (9-11 h/night), and one-year changes in physical fitness and body composition among overweight and obese children. Particularly, the study identified whether the number and specific combinations of 24-HMG adherence were associated with more favorable health outcomes in this high-risk pediatric group. A prospective cohort of 337 children aged 6-12 years from six public schools in China was followed for one year. Physical activity, sedentary screen time, and sleep were assessed using triaxial accelerometers, validated questionnaires, and parental reports. Physical fitness was evaluated via the Chinese National Student Physical Fitness Battery, while body composition i.e., body fat percentage (BFP), fat-free mass (FFM), and skeletal muscle mass (SMM), was measured using bioelectrical impedance analysis. Covariates included demographic characteristics and parental support for healthy movement behaviors. Over the follow-up, sleep duration decreased and sedentary time increased, while MVPA showed no significant change. All physical fitness and body composition indicators increased over the one-year period. Adherence to two guidelines, especially those including MVPA, was associated with reductions in BFP and gains in FFM. Combinations of MVPA with reduced sedentary time or adequate sleep showed the strongest associations with improvements in physical fitness and FFM and decreases in BFP. Full adherence to all three guidelines was associated only with improvements in physical fitness and FFM. This study demonstrates that adherence to the 24-HMG, particularly combinations involving MVPA, is associated with improved physical fitness and body composition in overweight and obese children. The underlying mechanisms and intervention evidence warrant further investigation.Level of evidence Level III-well-designed cohort study.