title: Does body mass index modify the association between physical activity and screen time with cardiometabolic risk factors in adolescents? Findings from a country-wide survey.
abstract: Moderate and vigorous physical activity (MVPA) and screen time (ST) have been associated with cardiometabolic health in youth. However, previous studies are conflicting whether these associations are independent of each other and it is unknown if they are modified by adiposity. We aimed to examine the independent and joint associations between MVPA and ST with cardiometabolic risk across body mass index (BMI) categories.
  
  
  
  A total of 36 956 Brazilian adolescents (12-17 years) from the Study of Cardiovascular Risks in Adolescents were included. Information on time spent in MVPA and ST were assessed by self-reports. Blood pressure, Homeostasis Model Assessment of Insulin Resistance, triglycerides, high-density lipoprotein-cholesterol and waist circumference were used to calculate a cardiometabolic risk score (sex-age-specific top-risk quintile for each biomarker). Ordered logistic regression was used to examine the associations.
  
  
  
  In final adjusted models, both higher MVPA (proportional odds ratio (POR)=0.80; 95% confidence interval (CI): 0.67-0.95) and ST (POR=1.23; 95% CI: 1.10-1.37) were independently associated with cardiometabolic risk. After stratification by normal weight vs overweight/obese, the inverse independent association for MVPA remained unchanged, whereas ST was positively associated with cardiometabolic risk only in overweight/obese adolescents (POR=1.62; 95% CI: 1.18-2.22). Participants who met the recommendations for both MVPA and ST had lower odds for cardiometabolic risk, especially if they were overweight/obese (POR=0.46; 95% CI: 0.31-0.68).
  
  
  
  MVPA and ST are independently associated with cardiometabolic risk; the association with ST, however, appears modified by BMI. Normal-weight adolescents should be encouraged to increase MVPA, whereas a combination of increasing MVPA and decreasing ST is recommended in those who are overweight or obese.
authors.affiliation: Postgraduate Program in Endocrinology, Universidade Federal do Rio Grande do Sul, Porto Alegre, Brazil.|Department of Sports Medicine, Norwegian School of Sports Science, Oslo, Norway.
authors.forename: F V
authors.initials: FV
authors.lastname: Cureau
authors.affiliation: Department of Sports Medicine, Norwegian School of Sports Science, Oslo, Norway.|Medical Research Council Epidemiology Unit, University of Cambridge, Cambridge, UK.
authors.forename: U
authors.initials: U
authors.lastname: Ekelund
authors.affiliation: Instituto de Estudos em Saúde Coletiva, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil.
authors.forename: K V
authors.initials: KV
authors.lastname: Bloch
authors.affiliation: Postgraduate Program in Endocrinology, Universidade Federal do Rio Grande do Sul, Porto Alegre, Brazil.|Endocrine Division, Hospital de Clínicas de Porto Alegre, Universidade Federal do Rio Grande do Sul, Porto Alegre, Brazil.
authors.forename: B D
authors.initials: BD
authors.lastname: Schaan
mesh_terms: D050154:Adiposity / Q000502:physiology; D000293:Adolescent; D015415:Biomarkers / Q000097:blood; D001794:Blood Pressure / Q000502:physiology*; D015992:Body Mass Index; D001938:Brazil / Q000453:epidemiology; D002318:Cardiovascular Diseases / Q000453:epidemiology / Q000209:etiology / Q000517:prevention & control*; D008076:Cholesterol, HDL / Q000097:blood; D003430:Cross-Sectional Studies; D015444:Exercise; D005260:Female; D006306:Health Surveys; D006801:Humans; D007333:Insulin Resistance / Q000502:physiology; D020407:Internet / Q000706:statistics & numerical data*; D008297:Male; D063766:Pediatric Obesity / Q000097:blood / Q000453:epidemiology / Q000517:prevention & control*; D012307:Risk Factors; D012572:School Health Services; D057185:Sedentary Behavior; D013690:Television / Q000706:statistics & numerical data*; D014280:Triglycerides / Q000097:blood; D055105:Waist Circumference
chemical_list: D015415:Biomarkers; D008076:Cholesterol, HDL; D014280:Triglycerides