Device-Measured Physical Activity, Sedentary Time, and Cardiometabolic Risk Markers in Youth: A Harmonized Individual Participant Data Meta-Analysis.

Importance: The evidence for benefits of higher physical activity and lower sedentary time on the cardiometabolic risk profile in youth is based on cross-sectional and small prospective studies. Objective: To determine the prospective associations between device-measured physical activity and sedentary time with later cardiometabolic risk profiles in youth. Data Sources: The International Children's Accelerometry Database and cohorts identified from a systematic literature search (final search performed December 2024). Study Selection: Studies measured physical activity and sedentary time with an accelerometer at baseline and had prospective data on at least 1 cardiometabolic risk marker. Data Extraction and Synthesis: Individual participant data were transferred to a secure network, harmonized, and analyzed as a single dataset using mixed linear regression models with different statistical adjustment based on directed acyclic graphs. Effect sizes are β coefficients per SD exposure increment. Main Outcomes and Measures: Body mass index (BMI); insulin, glucose, low-density lipoprotein (LDL) cholesterol, and triglyceride levels; and systolic blood pressure, analyzed individually and as composite scores. Results: Of 5432 records screened, 12 relevant studies were identified, of which 8 provided individual participant data. Fourteen cohorts (12 874 participants; mean [range] age, 10.4 [5.0-17.9] years; 6577 female [52%]) with a mean (SD) follow-up of 3.1 (2.0) years were included. Moderate to vigorous physical activity (per SD, 26 minutes/day) was inversely associated with insulin (-0.24 µIU/mL; 95% CI, -0.38 to -0.10 µIU/mL), LDL cholesterol level (-1.54 mg/dL; 95% CI, -1.93 to -0.77 mg/dL), triglyceride level (-1.77 mg/dL, 95% CI, -2.65 to -0.88 mg/dL), and the composite risk scores (-0.04; 95% CI, -0.06 to -0.02). However, moderate to vigorous physical activity was not associated with BMI (0.00; 95% CI, -0.005 to 0.005) and associated with a higher systolic blood pressure (0.25 mm Hg; 95% CI, 0.04-0.46 mm Hg). Associations for vigorous intensity activity were similar, except that there was no association with systolic blood pressure. Higher sedentary time was not associated with a worse cardiometabolic profile but was associated with lower blood glucose concentration (-0.36 mg/dL; 95% CI, -0.72 to 0 mg/dL) and lower systolic blood pressure (-0.90 mm Hg; 95% CI, -1.22 to -0.58 mm Hg). The magnitude and direction of associations were modified by modeling approach, sex, BMI, age, and follow-up time. Conclusions and Relevance: Results of this harmonized individual participant data meta-analysis suggest that physical activity of moderate and vigorous intensity was beneficially associated with some cardiometabolic risk markers during childhood and adolescence. However, associations were weak, sensitive to the modeling approach, and heterogeneous across subgroups. Sedentary time is unlikely an important determinant of cardiometabolic risk in youth.