title: Self-reported sitting time is associated with higher pressure from wave reflections independent of physical activity levels in healthy young adults.
abstract: BACKGROUND
  Time spent in sedentary pursuits such as sitting (SIT) is associated with an increased risk of cardiovascular disease independent of physical activity (PA). The purpose of this study was to examine the associations of PA and SIT with central hemodynamic burden in young adults.
  
  
  METHODS
  Aortic pressure waveforms were obtained using radial applanation tonometry and a generalized transfer function in 70 young healthy men (n = 41) and women (n = 29) (mean age = 23±1 years; body mass index = 24±1kg/m(2)). A wave separation technique that uses a physiologic pseudoaortic flow waveform was used to derive incident/forward wave pressure (Pf) and reflected/backward wave pressure (Pb). Levels of PA (metabolic equivalent, minutes per week) and SIT (sitting time per day) were obtained by self-report using the International Physical Activity Questionnaire.
  
  
  RESULTS
  A negative correlation existed between PA and Pf (r = -0.30; P < 0.05) and Pb (r = -0.36; P < 0.05). A positive correlation existed between SIT and Pf (r = 0.39; P < 0.05) and Pb (r = 0.44; P < 0.05). According to results from multiple regression, after adjusting for potential confounders (age, sex, height, heart rate, mean pressure) and PA, associations between SIT and Pf (P < 0.05) and SIT and Pb (P < 0.05) remained.
  
  
  CONCLUSIONS
  SIT is associated with higher forward wave pressure and backward wave pressure, 2 novel hemodynamic correlates of cardiovascular disease risk and target organ damage, in young apparently healthy men and women. This association is independent of PA.
authors.affiliation: Department of Exercise Science, Syracuse University, Syracuse, NY, USA. ksheffer@syr.edu
authors.forename: Kevin S
authors.initials: KS
authors.lastname: Heffernan
authors.forename: Brendan J
authors.initials: BJ
authors.lastname: Tarzia
authors.forename: Ari G
authors.initials: AG
authors.lastname: Kasprowicz
authors.forename: Wesley K
authors.initials: WK
authors.lastname: Lefferts
authors.forename: Miho
authors.initials: M
authors.lastname: Hatanaka
authors.forename: Sae Young
authors.initials: SY
authors.lastname: Jae
mesh_terms: D001011:Aorta / Q000502:physiology / Q000503:physiopathology*; D062186:Arterial Pressure / Q000502:physiology*; D005260:Female; D006801:Humans; D008297:Male; D008365:Manometry; D009043:Motor Activity / Q000502:physiology*; D063177:Pulse Wave Analysis; D057185:Sedentary Behavior; D055815:Young Adult
keywords: blood pressure; hypertension; physical activity; sitting time; wave reflection.