title: Association between objectively measured sedentary behavior and body mass index in preschool children.
abstract: OBJECTIVE
  To determine the association between accelerometry-derived sedentary behavior and body mass index (BMI) z-score in preschool children, and to determine whether the association changed when applying three different accelerometry cutpoints for sedentary behavior.
  
  
  METHODS
  Cross-sectional design. Data came from two completed studies: Children's Activity and Movement in Preschool Study (CHAMPS) and the Environmental Determinants of Physical Activity in Preschool Children (EDPAPC) study. Children of ages 3-5 years with complete data on sedentary behavior, BMI z-score, physical activity and other covariates were included in the analyses (N=263 in CHAMPS and N=155 in EDPAPC). Accelerometry data were summarized as time spent in sedentary behavior (min h(-1)) using three different cutpoints developed specifically for preschool children (<37.5, <200 and <373 counts per 15 s). Linear mixed regression models were used to determine the association between time spent in sedentary behavior and BMI z-score; age, gender, race, parental education, preschools and moderate-to-vigorous physical activity (MVPA) were included as covariates.
  
  
  RESULTS
  In both CHAMPS and EDPAPC studies, no independent association between time spent in sedentary behavior and BMI z-score was observed after adjusting for MVPA. The observed null association between sedentary behavior and BMI z-score was maintained even with different sedentary behavior cutpoints.
  
  
  CONCLUSIONS
  Regardless of cutpoints used, accelerometry-derived sedentary behavior was not independently associated with BMI z-score in two independent samples of preschool children. Longitudinal studies addressing this research question are needed.
authors: Department of Exercise Science, Arnold School of Public Health, University of South Carolina, Columbia, SC 29208, USA. byun@email.sc.edu
authors: W
authors: W
authors: Byun
authors: J
authors: J
authors: Liu
authors: R R
authors: RR
authors: Pate
mesh_terms: D061725:Accelerometry; D015992:Body Mass Index; D002652:Child Behavior; D002675:Child, Preschool; D003430:Cross-Sectional Studies; D004522:Educational Status; D015444:Exercise; D005260:Female; D015438:Health Behavior; D006801:Humans; D008297:Male; D009765:Obesity / Q000453:epidemiology / Q000517:prevention & control*; D015995:Prevalence; D012307:Risk Factors; D012574:Schools; D057185:Sedentary Behavior; D013997:Time Factors; D014481:United States / Q000453:epidemiology