title: Sedentary behavior and health outcomes: an overview of systematic reviews.
abstract: OBJECTIVE
  1) To synthesize the current observational evidence for the association between sedentary behavior and health outcomes using information from systematic reviews. 2) To assess the methodological quality of the systematic reviews found.
  
  
  RESULTS
  Medline; Excerpta Medica (Embase); PsycINFO; and Web of Science were searched for reviews published up to September 2013. Additional publications were provided by Sedentary Behaviour Research Network members. The methodological quality of the systematic reviews was evaluated using recommended standard criteria from AMSTAR. For each review, improper use of causal language in the description of their main results/conclusion was evaluated. Altogether, 1,044 review titles were identified, 144 were read in their entirety, and 27 were included. Based on the systematic reviews with the best methodological quality, we found in children and adolescents, strong evidence of a relationship between time spent in sedentary behavior and obesity. Moreover, moderate evidence was observed for blood pressure and total cholesterol, self-esteem, social behavior problems, physical fitness and academic achievement. In adults, we found strong evidence of a relationship between sedentary behavior and all-cause mortality, fatal and non-fatal cardiovascular disease, type 2 diabetes and metabolic syndrome. In addition, there is moderate evidence for incidence rates of ovarian, colon and endometrial cancers.
  
  
  CONCLUSIONS
  This overview based on the best available systematics reviews, shows that sedentary behavior may be an important determinant of health, independently of physical activity. However, the relationship is complex because it depends on the type of sedentary behavior and the age group studied. The relationship between sedentary behavior and many health outcomes remains uncertain; thus, further studies are warranted.
authors.affiliation: Departamento de Medicina Preventiva, Faculdade de Medicina da Universidade de São Paulo, São Paulo, Brasil; Centro de Estudos do Laboratório de Aptidão Fĩsica de São Caetano do Sul, São Caetano do Sul, Brasil.
authors.forename: Leandro Fornias Machado
authors.initials: LF
authors.lastname: de Rezende
authors.affiliation: Departamento de Medicina Preventiva, Faculdade de Medicina da Universidade de São Paulo, São Paulo, Brasil.
authors.forename: Maurício
authors.initials: M
authors.lastname: Rodrigues Lopes
authors.affiliation: Departamento de Medicina Preventiva, Faculdade de Medicina da Universidade de São Paulo, São Paulo, Brasil.
authors.forename: Juan Pablo
authors.initials: JP
authors.lastname: Rey-López
authors.affiliation: Centro de Estudos do Laboratório de Aptidão Fĩsica de São Caetano do Sul, São Caetano do Sul, Brasil.
authors.forename: Victor Keihan Rodrigues
authors.initials: VK
authors.lastname: Matsudo
authors.affiliation: Departamento de Medicina Preventiva, Faculdade de Medicina da Universidade de São Paulo, São Paulo, Brasil.
authors.forename: Olinda do Carmo
authors.initials: Odo C
authors.lastname: Luiz
mesh_terms: D000203:Activities of Daily Living; D000293:Adolescent; D000328:Adult; D005260:Female; D006304:Health Status; D006801:Humans; D008297:Male; D057185:Sedentary Behavior