Associations between cardiorespiratory fitness and cardiometabolic risk factors in children and adolescents with obesity

It is unclear if associations between cardiorespiratory fitness (CRF) and cardiometabolic risk factors are independent of degree of obesity, in children with obesity. The aim of this cross-sectional study on 151 children (36.4% girls), 9–17 years, from a Swedish obesity clinic, was to investigate associations between CRF and cardiometabolic risk factors, adjusted for body mass index standard deviation score (BMI SDS), in children with obesity. CRF was objectively assessed with the Åstrand-Rhyming submaximal cycle ergometer test, and blood samples (n = 96) and blood pressure (BP) (n = 84) according to clinical routine. Obesity specific reference values for CRF were used to create CRF levels. CRF was inversely associated with high-sensitivity C-reactive protein (hs-CRP), independent of BMI SDS, age, sex, and height. The inverse associations between CRF and diastolic BP did not remain significant when adjusted for BMI SDS. CRF and high-density lipoprotein cholesterol became inversely associated when adjusted for BMI SDS. Independent of degree of obesity, lower CRF is associated with higher levels of hs-CRP, as a biomarker of inflammation, in children with obesity and regular assessment of CRF should be encouraged. Future research in children with obesity should investigate if low-grade inflammation decreases when CRF is improved.