title: Blunted heart rate response to upright tilt in people with Down syndrome.
abstract: OBJECTIVE
  To determine whether heart rate and blood pressure responses to upright tilt would be lower in subjects with Down syndrome (DS) than in control subjects with no disabilities.
  
  
  METHODS
  Comparative study.
  
  
  METHODS
  University research laboratory.
  
  
  METHODS
  Nineteen people with DS (mean age, 25.1+/-7.3 y) and 17 control subjects without disabilities (mean age, 28.4+/-5.6 y).
  
  
  METHODS
  Not applicable.
  
  
  METHODS
  Heart rate and blood pressure recordings were obtained at rest and during a 2-minute period of passive head up tilt to 80 degrees .
  
  
  RESULTS
  Heart rate and blood pressure increased significantly during the first 30 seconds of upright tilt in both groups ( P <.05) and then stabilized for the remainder of the test. The initial heart rate response to head up tilt (first 30s) was significantly higher in controls compared with subjects with DS ( P <.05), whereas the blood pressure response did not differ between groups ( P >.05). Controlling for heart rate reserve showed a blunted heart rate response through the tilt period in subjects with DS.
  
  
  CONCLUSIONS
  These data show a blunted heart rate response to upright tilt in people with DS, despite similar changes in blood pressure, consistent with reduced sympathoexcitation and possibly altered baroreceptor function in these people with DS.
authors.affiliation: Exercise Science Department, Syracuse University, NY, USA. fernhall@uiuc.edu
authors.forename: Bo
authors.initials: B
authors.lastname: Fernhall
authors.forename: Arturo
authors.initials: A
authors.lastname: Figueroa
authors.forename: Scott
authors.initials: S
authors.lastname: Collier
authors.forename: Tracy
authors.initials: T
authors.lastname: Baynard
authors.forename: Ifigenia
authors.initials: I
authors.lastname: Giannopoulou
authors.forename: Styliani
authors.initials: S
authors.lastname: Goulopoulou
mesh_terms: D000293:Adolescent; D000328:Adult; D001794:Blood Pressure / Q000502:physiology; D004314:Down Syndrome / Q000503:physiopathology*; D005260:Female; D006339:Heart Rate / Q000502:physiology*; D006801:Humans; D008297:Male; D018667:Tilt-Table Test