title: Relationship of sitting time and physical activity with non-alcoholic fatty liver disease.
abstract: OBJECTIVE
  The goal of this study was to examine the association of sitting time and physical activity level with non-alcoholic fatty liver disease (NAFLD) in Korean men and women and to explore whether any observed associations were mediated by adiposity.
  
  
  METHODS
  A cross-sectional study was performed on 139,056 Koreans, who underwent a health examination between March 2011 and December 2013. Physical activity level and sitting time were assessed using the validated Korean version of the international Physical Activity Questionnaire Short Form. The presence of fatty liver was determined using ultrasonographic findings. Poisson regression models with robust variance were used to evaluate the association of sitting time and physical activity level with NAFLD.
  
  
  RESULTS
  Of the 139,056 subjects, 39,257 had NAFLD. In a multivariable-adjusted model, both prolonged sitting time and decreased physical activity level were independently associated with increasing prevalence of NAFLD. The prevalence ratios (95% CIs) for NAFLD comparing 5-9 and ⩾10 h/day sitting time to <5h/day were 1.04 (1.02-1.07) and 1.09 (1.06-1.11), respectively (p for trend <0.001). These associations were still observed in subjects with BMI <23 kg/m(2). The prevalence ratios (95% CIs) for NAFLD comparing minimally active and health-enhancing physically active groups to the inactive group were 0.94 (0.92-0.95) and 0.80 (0.78-0.82), respectively (p for trend <0.001).
  
  
  CONCLUSIONS
  Prolonged sitting time and decreased physical activity level were positively associated with the prevalence of NAFLD in a large sample of middle-aged Koreans, supporting the importance of reducing time spent sitting in addition to promoting physical activity.
authors.affiliation: Department of Occupational and Environmental Medicine, Kangbuk Samsung Hospital, Sungkyunkwan University, School of Medicine, Seoul, South Korea; Center for Cohort Studies, Total Healthcare Center, Kangbuk Samsung Hospital, Sungkyunkwan University, School of Medicine, Seoul, South Korea; Department of Clinical Research Design & Evaluation, SAIHST, Sungkyunkwan University, Seoul, South Korea. Electronic address: sh703.yoo@gmail.com.
authors.forename: Seungho
authors.initials: S
authors.lastname: Ryu
authors.affiliation: Department of Occupational and Environmental Medicine, Kangbuk Samsung Hospital, Sungkyunkwan University, School of Medicine, Seoul, South Korea; Center for Cohort Studies, Total Healthcare Center, Kangbuk Samsung Hospital, Sungkyunkwan University, School of Medicine, Seoul, South Korea; Department of Clinical Research Design & Evaluation, SAIHST, Sungkyunkwan University, Seoul, South Korea. Electronic address: yoosoo.chang@gmail.com.
authors.forename: Yoosoo
authors.initials: Y
authors.lastname: Chang
authors.affiliation: Center for Cohort Studies, Total Healthcare Center, Kangbuk Samsung Hospital, Sungkyunkwan University, School of Medicine, Seoul, South Korea.
authors.forename: Hyun-Suk
authors.initials: HS
authors.lastname: Jung
authors.affiliation: Center for Cohort Studies, Total Healthcare Center, Kangbuk Samsung Hospital, Sungkyunkwan University, School of Medicine, Seoul, South Korea.
authors.forename: Kyung Eun
authors.initials: KE
authors.lastname: Yun
authors.affiliation: Center for Cohort Studies, Total Healthcare Center, Kangbuk Samsung Hospital, Sungkyunkwan University, School of Medicine, Seoul, South Korea; Department of Laboratory Medicine, Kangbuk Samsung Hospital, Sungkyunkwan University, School of Medicine, Seoul, South Korea.
authors.forename: Min-Jung
authors.initials: MJ
authors.lastname: Kwon
authors.affiliation: Center for Cohort Studies, Total Healthcare Center, Kangbuk Samsung Hospital, Sungkyunkwan University, School of Medicine, Seoul, South Korea.
authors.forename: Yuni
authors.initials: Y
authors.lastname: Choi
authors.affiliation: Center for Cohort Studies, Total Healthcare Center, Kangbuk Samsung Hospital, Sungkyunkwan University, School of Medicine, Seoul, South Korea.
authors.forename: Chan-Won
authors.initials: CW
authors.lastname: Kim
authors.affiliation: Center for Cohort Studies, Total Healthcare Center, Kangbuk Samsung Hospital, Sungkyunkwan University, School of Medicine, Seoul, South Korea; Department of Clinical Research Design & Evaluation, SAIHST, Sungkyunkwan University, Seoul, South Korea.
authors.forename: Juhee
authors.initials: J
authors.lastname: Cho
authors.affiliation: Center for Cohort Studies, Total Healthcare Center, Kangbuk Samsung Hospital, Sungkyunkwan University, School of Medicine, Seoul, South Korea.
authors.forename: Byung-Seong
authors.initials: BS
authors.lastname: Suh
authors.affiliation: Division of Gastroenterology and Hepatology, Department of Internal Medicine, Kangbuk Samsung Hospital, Sungkyunkwan University, School of Medicine, Seoul, South Korea.
authors.forename: Yong Kyun
authors.initials: YK
authors.lastname: Cho
authors.affiliation: Center for Cohort Studies, Total Healthcare Center, Kangbuk Samsung Hospital, Sungkyunkwan University, School of Medicine, Seoul, South Korea; Department of Radiology, Kangbuk Samsung Hospital, Sungkyunkwan University, School of Medicine, Seoul, South Korea.
authors.forename: Eun Chul
authors.initials: EC
authors.lastname: Chung
authors.affiliation: Center for Cohort Studies, Total Healthcare Center, Kangbuk Samsung Hospital, Sungkyunkwan University, School of Medicine, Seoul, South Korea; Department of Family Medicine, Kangbuk Samsung Hospital, Sungkyunkwan University, School of Medicine, Seoul, South Korea.
authors.forename: Hocheol
authors.initials: H
authors.lastname: Shin
authors.affiliation: Department of Physical Education, Seoul National University, Seoul, South Korea.
authors.forename: Yeon Soo
authors.initials: YS
authors.lastname: Kim
mesh_terms: D000328:Adult; D015992:Body Mass Index; D003430:Cross-Sectional Studies; D018450:Disease Progression; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D015994:Incidence; D008297:Male; D009043:Motor Activity / Q000502:physiology*; D065626:Non-alcoholic Fatty Liver Disease / Q000453:epidemiology* / Q000503:physiopathology; D015995:Prevalence; D056910:Republic of Korea / Q000453:epidemiology; D012146:Rest / Q000502:physiology*; D012189:Retrospective Studies; D012307:Risk Factors; D011795:Surveys and Questionnaires; D013997:Time Factors
keywords: NAFLD; Obesity; Physical activity; Sitting time