title: Circulating irisin levels are positively associated with metabolic risk factors in sedentary subjects.
abstract: BACKGROUND
  A physically active life-style plays an independent role in the protection against type 2 diabetes and cardiovascular diseases. Irisin, a novel exercise-induced myokine, activates thermogenesis in rodents through increasing beige fat cells abundance within white fat. We aimed to investigate circulating irisin levels in association with the degree of physical activity and various metabolic parameters in humans.
  
  
  METHODS
  Circulating irisin levels (ELISA) and metabolic parameters were analyzed in 428 subjects (195 men/233 women). Participants were classified according to their self-reported physical activity and to their area of residence.
  
  
  RESULTS
  Circulating irisin levels were higher in active than in sedentary subjects (p = 0.006). Rural inhabitants showed higher circulating irisin levels than urban subjects (p < 0.0001). The increase in irisin levels related to an active lifestyle was only observed in rural citizens (p = 0.014). Among sedentary participants, irisin levels were positively associated with metabolic risk factors (BMI, fasting insulin, HOMA and fasting triglycerides). The area of residence (β = - 0.592, p = < 0.0001) contributed independently to circulating irisin levels variance after controlling for age, gender, BMI, HOMAIR, triglycerides and physical activity.
  
  
  CONCLUSIONS
  In sedentary participants, circulating irisin levels were positively associated with parameters related to an increased cardiometabolic risk. The present study confirmed that an active lifestyle increases circulating irisin levels, but only among subjects living in a rural environment. Area of residence might be a determinant of irisin levels.
authors.affiliation: Department of Diabetes, Endocrinology and Nutrition, Institut d'Investigació Biomèdica de Girona (IdIBGi), CIBEROBN (CB06/03/010) and Instituto de Salud Carlos III (ISCIII), Girona, Spain.
authors.forename: María
authors.initials: M
authors.lastname: Moreno
authors.affiliation: Department of Diabetes, Endocrinology and Nutrition, Institut d'Investigació Biomèdica de Girona (IdIBGi), CIBEROBN (CB06/03/010) and Instituto de Salud Carlos III (ISCIII), Girona, Spain.
authors.forename: José María
authors.initials: JM
authors.lastname: Moreno-Navarrete
authors.affiliation: Department of Diabetes, Endocrinology and Nutrition, Institut d'Investigació Biomèdica de Girona (IdIBGi), CIBEROBN (CB06/03/010) and Instituto de Salud Carlos III (ISCIII), Girona, Spain.
authors.forename: Marta
authors.initials: M
authors.lastname: Serrano
authors.affiliation: Department of Diabetes, Endocrinology and Nutrition, Institut d'Investigació Biomèdica de Girona (IdIBGi), CIBEROBN (CB06/03/010) and Instituto de Salud Carlos III (ISCIII), Girona, Spain.
authors.forename: Francisco
authors.initials: F
authors.lastname: Ortega
authors.affiliation: Department of Endocrinology and Nutrition, Hospital Central de Asturias, Oviedo, Spain.
authors.forename: Elías
authors.initials: E
authors.lastname: Delgado
authors.affiliation: Department of Endocrinology and Nutrition, Hospital Central de Asturias, Oviedo, Spain.
authors.forename: Cecilia
authors.initials: C
authors.lastname: Sanchez-Ragnarsson
authors.affiliation: Endocrinology and Nutrition, Hospital Regional de Málaga, IBIMA, CIBERDEM, Spain.
authors.forename: Sergio
authors.initials: S
authors.lastname: Valdés
authors.affiliation: Department of Medicine, Hospital San Agustin, Aviles, Spain.
authors.forename: Patricia
authors.initials: P
authors.lastname: Botas
authors.affiliation: Department of Diabetes, Endocrinology and Nutrition, Institut d'Investigació Biomèdica de Girona (IdIBGi), CIBEROBN (CB06/03/010) and Instituto de Salud Carlos III (ISCIII), Girona, Spain.
authors.forename: Wifredo
authors.initials: W
authors.lastname: Ricart
authors.affiliation: Department of Diabetes, Endocrinology and Nutrition, Institut d'Investigació Biomèdica de Girona (IdIBGi), CIBEROBN (CB06/03/010) and Instituto de Salud Carlos III (ISCIII), Girona, Spain.
authors.forename: José Manuel
authors.initials: JM
authors.lastname: Fernández-Real
mesh_terms: D000328:Adult; D000368:Aged; D002318:Cardiovascular Diseases / Q000097:blood; D003924:Diabetes Mellitus, Type 2 / Q000097:blood; D005260:Female; D005353:Fibronectins / Q000097:blood*; D006801:Humans; D007333:Insulin Resistance; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D012307:Risk Factors; D012424:Rural Population; D057185:Sedentary Behavior
chemical_list: C577593:FNDC5 protein, human; D005353:Fibronectins