title: Body position influences the maximum inspiratory and expiratory mouth pressures of young healthy subjects.
abstract: OBJECTIVE
  The purpose of this study was to determine the effects of body position on respiratory muscle strength of young healthy subjects.
  
  
  METHODS
  Sixty-three (50 female, mean age 19.7±1.5 years) healthy subjects participated in the study.
  
  
  METHODS
  Participants were measured in the sitting position, semi-upright sitting position, and in the supine position. The order of the three conditions was randomly determined.
  
  
  METHODS
  Maximal inspiratory and expiratory mouth pressures (PImax, PEmax) and lung function.
  
  
  RESULTS
  A significant effect of body position was observed on PEmax values, controlling for gender. PImax in the sitting position (92.8±20.05 cm H2O) was significantly higher than in the supine (84.1±15.1 cm H2O; mean difference: 8.70, 95% CI [5.95, 12.45], p<0.001) and semi-upright sitting positions (84.4±17.5 cm H2O; mean difference: 8.43, 95% CI [5.78, 11.07], p<0.001). PEmax was also significantly higher in the sitting position (125.4±34.2 cm H2O) than in the supine (115.8±29.0 cm H2O; mean difference: 9.59, 95% CI [4.86, 14.32], p<0.001) and semi-upright sitting positions (120.2±33.9 cm H2O; mean difference: 5.21, 95% CI [0.87, 9.54], p=0.013).
  
  
  CONCLUSIONS
  Body position influences respiratory muscle strength of young healthy subjects. PImax and PEmax are higher in the sitting position than in the supine or semi-upright sitting positions.
authors.affiliation: School of Health Sciences, University of Aveiro, Aveiro, Portugal. Electronic address: rcosta@ua.pt.
authors.forename: Rui
authors.initials: R
authors.lastname: Costa
authors.affiliation: School of Health Sciences, University of Aveiro, Aveiro, Portugal.
authors.forename: Nádia
authors.initials: N
authors.lastname: Almeida
authors.affiliation: School of Health Sciences, University of Aveiro, Aveiro, Portugal.
authors.forename: Fernando
authors.initials: F
authors.lastname: Ribeiro
mesh_terms: D000293:Adolescent; D045853:Exhalation / Q000502:physiology*; D005260:Female; D064368:Healthy Volunteers; D006801:Humans; D001239:Inhalation / Q000502:physiology*; D008297:Male; D009055:Mouth / Q000502:physiology*; D053580:Muscle Strength; D011187:Posture / Q000502:physiology*; D011312:Pressure; D012132:Respiratory Muscles / Q000502:physiology*; D055815:Young Adult
keywords: Expiration; Inspiration; Posture; Respiratory muscles