title: Obesity as a mediator of the influence of cardiorespiratory fitness on cardiometabolic risk: a mediation analysis.
abstract: OBJECTIVE
  The relationship between cardiorespiratory fitness (CRF) and metabolic syndrome (MetS) is well known, although the extent to which body weight may act as a confounder or mediator in this relationship is uncertain. The aim of this study was to examine whether the association between CRF and cardiometabolic risk factors is mediated by BMI.
  
  
  METHODS
  A cross-sectional study including 1,158 schoolchildren aged 8-11 years from the province of Cuenca, Spain, was undertaken. We measured height, weight, waist circumference (WC), blood pressure, fasting plasma lipid profile and insulin, and CRF (20-m shuttle run test). A validated cardiometabolic risk index was estimated by summing standardized z scores of WC, log triglyceride-to-HDL cholesterol ratio (TG/HDL-c), mean arterial pressure (MAP), and log fasting insulin. To assess whether the association between CRF and cardiometabolic risk was mediated by BMI, linear regression models were fitted according to Baron and Kenny procedures for mediation analysis.
  
  
  RESULTS
  In girls, BMI acts as a full mediator in the relationship between CRF and cardiometabolic risk factors, with the exception of log TG/HDL-c ratio. In boys, BMI acts as a full mediator in the relationship between CRF and both log TG/HDL-c ratio and MAP, and as a partial mediator in the relationship between CRF and cardiometabolic risk factors.
  
  
  CONCLUSIONS
  BMI mediates the association between CRF and MetS in schoolchildren. Overall, good levels of CRF are associated with lower cardiometabolic risk, particularly when accompanied by weight reduction.
authors.affiliation: Corresponding author: Vicente Martínez-Vizcaíno, vicente.martinez@uclm.es.
authors.forename: Ana
authors.initials: A
authors.lastname: Díez-Fernández
authors.forename: Mairena
authors.initials: M
authors.lastname: Sánchez-López
authors.forename: Ricardo
authors.initials: R
authors.lastname: Mora-Rodríguez
authors.forename: Blanca
authors.initials: B
authors.lastname: Notario-Pacheco
authors.forename: Coral
authors.initials: C
authors.lastname: Torrijos-Niño
authors.forename: Vicente
authors.initials: V
authors.lastname: Martínez-Vizcaíno
mesh_terms: D015992:Body Mass Index; D002318:Cardiovascular Diseases / Q000453:epidemiology*; D002648:Child; D003430:Cross-Sectional Studies; D005080:Exercise Test; D005260:Female; D006321:Heart / Q000502:physiology*; D006801:Humans; D008297:Male; D024821:Metabolic Syndrome / Q000453:epidemiology*; D009765:Obesity / Q000097:blood / Q000453:epidemiology* / Q000503:physiopathology; D010809:Physical Fitness / Q000502:physiology*; D012143:Respiratory Physiological Phenomena; D012307:Risk Factors; D013030:Spain