Association Between Physical Fitness and Cardiovascular Health in Chilean Schoolchildren from the Metropolitan Region

Background: Cardiovascular diseases increasingly impact youth, with early development of risk factors such as obesity, hypertension, and inadequate nutrient intake. Proper nutrient intake and physical fitness are vital for reducing these risks, especially in pediatric populations. This study explores the connection between physical fitness, metabolic risk, and nutrient status among 1656 Chilean schoolchildren from diverse socio-economic backgrounds. Methods: Anthropometric measures included weight, height, skinfold thickness, waist circumference, and blood pressure. Physical fitness was assessed via handgrip strength, standing long jump, and a six-minute walk test. Nutrient intake was also evaluated, and a composite metabolic risk score was calculated based on waist circumference, skinfolds, and blood pressure. Results: Boys consistently outperformed girls in physical fitness tests, including grip strength and horizontal jump, with differences becoming more pronounced in higher grades and Tanner stages. Girls exhibited higher subcutaneous fat levels and obesity prevalence during later grades, highlighting gender-specific patterns in body composition. Better physical fitness was associated with lower waist circumference, skinfold thickness, and metabolic risk scores. A moderate correlation between aerobic fitness (distance/height) and blood pressure (r = 0.27, p = 0.01) was observed. Z-Score MR analysis revealed that students in the lowest fitness tertile exhibited significantly higher cardiovascular risk profiles compared to their fitter peers. Conclusions: Physical fitness plays a critical role in reducing cardiovascular risk in children. The findings underscore the importance of promoting gender- and age-specific interventions that include both aerobic and strength-based physical activities. Comprehensive school programs focusing on nutrition and physical activity are essential to mitigating cardiovascular risk and promoting long-term health outcomes. Future longitudinal studies are recommended to establish causal relationships and evaluate the impact of targeted interventions.