Introduction & Purpose: Evidence regarding the associations of physical activity and sedentary time with cardiometabolic risk profiles in children and adolescents is mainly derived from cross-sectional studies and a limited number of prospective studies. This study aimed to investigate the prospective associations of accelerometer-measured physical activity and sedentary time with subsequent cardiometabolic risk markers in youth.

Methodology: This harmonized individual participant data meta-analysis included 14 prospective cohort studies and 12,874 participants. The mean age was 10.4 years (range, 5.0–17.9 years), and the mean follow-up duration was 3.1 years. Moderate-to-vigorous physical activity, vigorous physical activity, and sedentary time were measured using accelerometers. Outcome measures included body mass index, insulin, glucose, low-density lipoprotein cholesterol, triglycerides, and systolic blood pressure. Data were analyzed using linear mixed-effects regression models with different levels of statistical adjustment.

Results: Moderate-to-vigorous physical activity, per 1-SD increase (equivalent to 26 minutes per day), was inversely associated with insulin, low-density lipoprotein cholesterol, triglycerides, and clustered risk scores. It was not associated with body mass index but was associated with higher systolic blood pressure. Associations for vigorous physical activity were similar, except that no significant association with systolic blood pressure was observed. Higher sedentary time was not associated with a worse cardiometabolic risk profile. The magnitude and direction of associations varied according to the modeling approach, sex, body mass index, age, and follow-up duration.

Conclusion: Moderate- and vigorous-intensity physical activity showed weak but favorable associations with some cardiometabolic risk markers during childhood and adolescence. These associations were sensitive to the modeling approach and heterogeneous across subgroups. Sedentary time is unlikely to be an important determinant of cardiometabolic risk in youth.