title: The relationship between utilitarian walking, utilitarian cycling, and body mass index in a population based cohort study of adults: comparing random intercepts and fixed effects models.
abstract: OBJECTIVE
  To examine associations between utilitarian walking, utilitarian cycling, leisure time physical activity and body mass index (BMI).
  
  
  METHODS
  Participants from the National Population Health Survey (NPHS) of Statistics Canada were interviewed by telephone every two years from 1994 to 2010. Analysis includes data from 6894 living participants aged 18-64years. Fixed effects and random intercepts models examined the association between BMI, utilitarian walking, and utilitarian cycling, controlling for behavioral and sociodemographic factors.
  
  
  RESULTS
  The final adjusted fixed effects models showed no significant relationship between utilitarian walking and BMI. In the unbalanced sample utilitarian cycling for 1 to 5h per week (b=-0.15, 95% CI: -0.28 to -0.02), and more than 5h per week (b=-0.22, 95% CI: -0.44 to 0.00) was significantly associated with BMI over time. In the fully balanced sample utilitarian cycling for 1 to 5h per week (b=-0.12, 95% CI: -0.27 to 0.03), more than 5h per week (b=-0.16, 95% CI: -0.45 to 0.13) was not significantly associated with BMI over time.
  
  
  CONCLUSIONS
  The results suggest that utilitarian walking is not related to BMI. The relationship between utilitarian cycling and BMI is less clear.
authors.affiliation: Department of Community Health and Epidemiology, University of Saskatchewan, Saskatoon, Canada. Electronic address: daniel.fuller@usask.ca.
authors.forename: Daniel
authors.initials: D
authors.lastname: Fuller
authors.affiliation: Department of Community Health Sciences, University of Nevada, Reno, USA; Department of Social and Behavioral Sciences, Harvard School of Public Health, Boston, USA.
authors.forename: Roman
authors.initials: R
authors.lastname: Pabayo
mesh_terms: D000293:Adolescent; D000328:Adult; D001642:Bicycling / Q000502:physiology*; D015992:Body Mass Index; D002170:Canada; D015331:Cohort Studies; D005260:Female; D006801:Humans; D007899:Leisure Activities; D008297:Male; D008875:Middle Aged; D015233:Models, Statistical; D009043:Motor Activity; D012307:Risk Factors; D014186:Transportation / Q000379:methods; D016138:Walking / Q000502:physiology*; D055815:Young Adult
keywords: Adult; Body mass index; Longitudinal studies; Transportation