Cardiometabolic Risk in Children and Adolescents: The Paradox between Body Mass Index and Cardiorespiratory Fitness

Background: Cardiometabolic risk has been shown to be inversely associated with cardiorespiratory fitness (CRF) and positively associated with body mass index (BMI). Objective: Our objective was to analyze the association of cardiometabolic risk factors with combined BMI and CRF in schoolchildren from a city in southern Brazil. Methods: Cross-sectional study with a sample of 1252 schoolchildren aged seven to 17 years. Total cholesterol (TC), HDL-c, LDL-c, triglycerides (TG), systolic (SBP) and diastolic blood pressure (DBP) were evaluated. CRF and BMI were grouped into one variable and the schoolchildren were classified as eutrophic/fit, eutrophic/unfit, overweight-obese/fit, and overweight-obese/unfit. Crude and adjusted analyzes were performed using Poisson Regression and an alpha of 0.05 was adopted. Results: Overweight-obese and fit schoolchildren showed a prevalence ratio (PR) of 1.50 (1.04 - 2.16) for altered TG, 3.05 (2.05 - 4.54) for elevated SBP, and 2.70 (1.87 - 3.88) for elevated DBP. Overweight-obese and unfit schoolchildren showed a PR for high TC of 1.24 (1.11 - 1.39) and 1.51(1.11 - 2.04) for low HDL levels. In addition, they had a risk of 2.07 (1.60 - 2.69) for altered TG, 3.36 (2.31 - 4.60) for elevated SBP and 2.42 (1.76 - 3.32) for altered DBP. Conclusion: BMI played a central role in the association with risk and CRF was shown to attenuate the association between risk factors and obesity. Overweight-obese children and adolescents had a higher cardiometabolic risk, but the effect size was larger among the unfit.