title: Normal values for respiratory muscle strength in healthy preschoolers and school children.
abstract: OBJECTIVE
  To generate reference values for respiratory muscle strength in healthy children aged three to twelve years.
  
  
  METHODS
  Participants were recruited from three schools and selected after a respiratory disease questionnaire analysis and written informed consent by parents or guardians. All participants included in the study had normal spirometry, height and weight were measured on the same day. Respiratory muscle strength was evaluated by a single examiner following the guidelines for pulmonary function tests. The association between MIP and MEP values with the potential predictive variables was analyzed using a multiple linear regression model.
  
  
  RESULTS
  A total of 171 participants were selected and distributed evenly by age. The age, height, weight and forced vital capacity showed moderate to strong correlations with both respiratory pressures. However, the regression model showed that height and weight were the best variables to predict MIP in both sexes, and age and weight to predict MEP. The power of prediction (R²) ranged from 46 to 58%. The intraclass correlation coefficient was used in a subgroup and demonstrated excellent reproducibility between tests.
  
  
  CONCLUSIONS
  The results of this study demonstrate that the behavior of respiratory muscle strength in healthy preschool and school children can be explained by age, height and weight.
authors.affiliation: Graduate Program of Pediatrics and Children's Health, Pontifícia Universidade Católica do Rio Grande do Sul-PUCRS, Porto Alegre, Rio Grande do Sul, Brazil.
authors.forename: João Paulo
authors.initials: JP
authors.lastname: Heinzmann-Filho
authors.forename: Paula Cristina
authors.initials: PC
authors.lastname: Vasconcellos Vidal
authors.forename: Marcus Herbert
authors.initials: MH
authors.lastname: Jones
authors.forename: Márcio Vinícius Fagundes
authors.initials: MV
authors.lastname: Donadio
mesh_terms: D000704:Analysis of Variance; D002648:Child; D002675:Child, Preschool; D003430:Cross-Sectional Studies; D005260:Female; D006304:Health Status; D006801:Humans; D008297:Male; D053580:Muscle Strength / Q000502:physiology*; D012016:Reference Values; D012129:Respiratory Function Tests; D012132:Respiratory Muscles / Q000502:physiology*