LAUSR

Given the growing relevance of physical fitness for cardiometabolic health in children with obesity and the rising prevalence of MetS, this study aimed to explore the relationship between physical fitness and MetS. Specifically, the goal was to assess the relationship between physical fitness and the severity of MetS, as measured by the MetS risk score, and to evaluate the importance of each dimension as a potential indicator of metabolic health in the pediatric population. We consecutively recruited a total of 62 children and adolescents (aged 7–17 years) with obesity (BMI z-score > 2SD). For all the patients, we evaluated cardiorespiratory fitness, muscular strength, and speed-agility. We computed the MetS risk score, a continuous risk score based on BMI z-score, HDL-C, systolic blood pressure, triglycerides, and fasting glucose, and MetS was defined as having a z-score > 0.75. Cardiorespiratory fitness and speed-agility were not significantly associated with MetS. Lower limb muscular strength, measured by the standing broad jump, was inversely associated with the odds of having MetS (OR: 0.47; 0.22–0.88; 95% CI), with a 1SD (24 cm) increase in SBJ corresponding to a 53% reduction in risk. Additionally, cardiorespiratory fitness was not related to any cardiometabolic outcomes (p > 0.05), whereas muscular strength showed an inverse association with the MetS risk score (β2 =  − 0.266, p = 0.043), BMI z-score (β2 =  − 0.443, p = 0.001), SBP (β2 =  − 0.304, p = 0.020), and waist-to-height ratio (β2 =  − 0.328, p = 0.012). Conclusion: We demonstrated a link between MetS and physical fitness in children with obesity, with muscular strength showing a stronger association compared to cardiorespiratory fitness and speed-agility. The findings support the role of muscle integrity in metabolic health, emphasizing the importance of educating individuals from an early age about daily PA to promote lifelong healthy habits. What is Known: • Physical fitness is associated with improved cardiometabolic outcomes in children and adolescents with obesity. • Muscular strength, as one domain of physical fitness, has been linked to metabolic health, but findings are inconsistent and often context-dependent. What is New: • This study shows that muscular strength, specifically lower limb strength measured by standing broad jump, is inversely associated with metabolic syndrome severity in children with obesity. • Cardiorespiratory fitness and speed-agility did not show significant associations in our sample, possibly due to limited variability or generally low levels; nonetheless, muscular strength emerged as a noteworthy fitness domain related to metabolic risk in this population. What is Known: • Physical fitness is associated with improved cardiometabolic outcomes in children and adolescents with obesity. • Muscular strength, as one domain of physical fitness, has been linked to metabolic health, but findings are inconsistent and often context-dependent. What is New: • This study shows that muscular strength, specifically lower limb strength measured by standing broad jump, is inversely associated with metabolic syndrome severity in children with obesity. • Cardiorespiratory fitness and speed-agility did not show significant associations in our sample, possibly due to limited variability or generally low levels; nonetheless, muscular strength emerged as a noteworthy fitness domain related to metabolic risk in this population.