Does cardiorespiratory fitness moderate the prospective association between physical activity and cardiometabolic risk factors in children?

Background/Objectives Physical activity (PA) and cardiorespiratory fitness (CRF) are independently associated with reduced cardiometabolic risk in children, and may affect risk through different pathways. This study aims to examine if CRF moderate the prospective association between PA, sedentary time, and cardiometabolic outcomes in 10-year-old children. Subjects/Methods In total, 718 children of 1129 (drop out n = 7) had valid measures of PA (accelerometry), CRF (the Andersen running test), and a cardiometabolic risk profile measured at baseline and follow-up 7 months later. Cardiometabolic outcomes were systolic blood pressure, waist circumference (WC), total cholesterol, high-density lipoprotein, triglycerides, glucose, and insulin (HOMA-IR). The cardiometabolic risk factors were analysed individually, and as a clustered risk score ( z score). A linear mixed model was used to examine the prospective associations between different PA exposures (overall PA, sedentary time, moderate-to-vigorous PA (MVPA), vigorous PA) and cardiometabolic outcomes, including the interaction term PA × CRF in the model to assess moderation by CRF. Results CRF modified the association for baseline overall PA ( P