Effectiveness of Physical Activity and Lifestyle Interventions in Pediatric Populations at Cardiovascular Risk: A Systematic Review and Meta-Analysis

Background/Objectives: Children at cardiovascular risk require effective non-pharmacological strategies to improve cardiometabolic health. This study aimed to evaluate the effectiveness of physical activity and lifestyle-based interventions on blood pressure and related cardiovascular risk markers in children and adolescents. Materials and Methods: A systematic review and meta-analysis were conducted in accordance with PRISMA guidelines and registered in PROSPERO (CRD42025644256). Searches were performed in MEDLINE (PubMed), SPORTDiscus (EBSCO), and the Cochrane Library from January 2015 to March 2025. Methodological quality and risk of bias were evaluated using the PEDro scale, RoB 2.0, and GRADE. Results: Twenty-nine studies were included, showing overall high methodological quality. Pooled analyses showed a statistically significant reduction in systolic blood pressure (SMD = −0.35; 95% CI: −0.40 to −0.31; p < 0.00001, I2 = 83%). Diastolic blood pressure also showed a small but statistically significant reduction (SMD = −0.06; 95% CI: −0.11 to −0.01; p = 0.01; I2 = 93%), equivalent to an estimated decrease of about 1 mmHg. Fasting insulin levels were significantly reduced (SMD = −0.92; 95% CI: −1.27 to −0.56; p < 0.00001), suggesting improvements in metabolic regulation despite considerable heterogeneity (I2 = 95%). In contrast, pooled effects for body fat percentage (%) (SMD = 0.11; 95% CI: −0.10 to 0.32; p = 0.31) and BMI z-score (standardized units) (SMD = 0.13; 95% CI: −0.04 to 0.31; p = 0.14) were not statistically significant, with very high between-study variability. Conclusions: Multicomponent interventions integrating physical activity with lifestyle modification appear effective in reducing systolic and diastolic blood pressure and improving insulin sensitivity in children and adolescents at elevated cardiovascular risk. Although the magnitude of blood pressure reductions is modest, even small decreases at the population level may contribute to meaningful long-term cardiovascular risk reductions.