title: Reproducibility of inspiratory muscle endurance testing using PowerBreathe for COPD patients.
abstract: BACKGROUND
  Assessing the strength and endurance of respiratory muscles is fundamental for characterizing respiratory muscle dysfunction. Although a variety of tests are used to evaluate respiratory muscle endurance, not all of them are applicable in clinical practice. Assessments can be made using a practical device called PowerBreathe®, but its reproducibility has not been tested in chronic obstructive pulmonary disease (COPD) patients.
  
  
  OBJECTIVE
  To verify the reproducibility of the inspiratory muscle endurance test using a manometer and PowerBreathe® in COPD patients.
  
  
  METHODS
  A cross-sectional study was used. In total, 19 moderate-severe COPD patients, male and female, aged 50 to 80 years took part in the research. This evaluation consisted of 2 tests: an incremental test and a constant one held on the same day and repeated after 48 hr. The incremental test started with 10-cm H2O, adding 10-cm H2O every 2 min and taking 1 min of rest before increasing the load. The highest load that could be sustained for at least 1 min was considered the sustained maximum inspiratory pressure (SMIP) value. The constant test was performed at an intensity of 80% of the SMIP and the maximum time limit was 30 min.
  
  
  RESULTS
  In the incremental test, there was a significant increase in the SMIP compared to the test-retest (61 ± 24/64.7 ± 23.8; p = .015); the value of the relative reproducibility was 0.96, the standard error of the absolute measurement was 4.7 (95% confidence interval 9.2), and the minimum detectable difference was 10.9. In the Bland-Altman analysis, the mean error was 4.2 (confidence interval -7.6 to 16.1). The constant test was not reproducible.
  
  
  CONCLUSIONS
  It was observed that the incremental test was reproducible to evaluate inspiratory muscle endurance in COPD patients. Furthermore, 2 tests needed to be carried out due to the learning effect.
authors.affiliation: Spirometry and Respiratory Physiotherapy Laboratory-LEFiR, Universidade Federal de São Carlos-UFSCar, São Carlos, São Paulo, Brazil.
authors.forename: Renata P
authors.identifier: http://orcid.org/0000-0001-6523-6354
authors.initials: RP
authors.lastname: Basso-Vanelli
authors.affiliation: Spirometry and Respiratory Physiotherapy Laboratory-LEFiR, Universidade Federal de São Carlos-UFSCar, São Carlos, São Paulo, Brazil.
authors.forename: Valéria A P
authors.initials: VAP
authors.lastname: Di Lorenzo
authors.affiliation: Spirometry and Respiratory Physiotherapy Laboratory-LEFiR, Universidade Federal de São Carlos-UFSCar, São Carlos, São Paulo, Brazil.
authors.forename: Mariane
authors.initials: M
authors.lastname: Ramalho
authors.affiliation: Spirometry and Respiratory Physiotherapy Laboratory-LEFiR, Universidade Federal de São Carlos-UFSCar, São Carlos, São Paulo, Brazil.
authors.forename: Ivana G
authors.initials: IG
authors.lastname: Labadessa
authors.affiliation: Centro Universitário UNIFAFIBE, Bebedouro, São Paulo, Brazil.|Centro Universitário Claretiano, Batatais, São Paulo, Brazil.
authors.forename: Eloisa M G
authors.initials: EMG
authors.lastname: Regueiro
authors.affiliation: Spirometry and Respiratory Physiotherapy Laboratory-LEFiR, Universidade Federal de São Carlos-UFSCar, São Carlos, São Paulo, Brazil.
authors.forename: Mauricio
authors.initials: M
authors.lastname: Jamami
authors.affiliation: Spirometry and Respiratory Physiotherapy Laboratory-LEFiR, Universidade Federal de São Carlos-UFSCar, São Carlos, São Paulo, Brazil.|Universidade Nove de Julho-UNINOVE, São Paulo, São Paulo, Brazil.
authors.forename: Dirceu
authors.initials: D
authors.lastname: Costa
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D003430:Cross-Sectional Studies; D017079:Exercise Tolerance; D005260:Female; D006801:Humans; D001239:Inhalation; D008297:Male; D008365:Manometry; D008875:Middle Aged; D010807:Physical Endurance; D029424:Pulmonary Disease, Chronic Obstructive / Q000503:physiopathology*; D015203:Reproducibility of Results; D012129:Respiratory Function Tests; D012132:Respiratory Muscles / Q000502:physiology*
keywords: COPD; muscle endurance test; respiratory muscles; test-retest reproducibility