title: Respiratory muscle endurance is limited by lower ventilatory efficiency in post-myocardial infarction patients.
abstract: BACKGROUND
  Reduced respiratory muscle endurance (RME) contributes to increased dyspnea upon exertion in patients with cardiovascular disease.
  
  
  OBJECTIVE
  The objective was to characterize ventilatory and metabolic responses during RME tests in post-myocardial infarction patients without respiratory muscle weakness.
  
  
  METHODS
  Twenty-nine subjects were allocated into three groups: recent myocardial infarction group (RG, n=9), less-recent myocardial infarction group (LRG, n=10), and control group (CG, n=10). They underwent two RME tests (incremental and constant pressure) with ventilatory and metabolic analyses. One-way ANOVA and repeated measures one-way ANOVA, both with Tukey post-hoc, were used between groups and within subjects, respectively.
  
  
  RESULTS
  Patients from the RG and LRG presented lower metabolic equivalent and ventilatory efficiency than the CG on the second (50± 06, 50± 5 vs. 42± 4) and third part (50± 11, 51± 10 vs. 43± 3) of the constant pressure RME test and lower metabolic equivalent during the incremental pressure RME test. Additionally, at the peak of the incremental RME test, RG patients had lower oxygen uptake than the CG.
  
  
  CONCLUSIONS
  Post-myocardial infarction patients present lower ventilatory efficiency during respiratory muscle endurance tests, which appears to explain their inferior performance in these tests even in the presence of lower pressure overload and lower metabolic equivalent.
authors.affiliation: Cardiovascular Physical Therapy Laboratory, Nucleus of Research in Physical Exercise, Universidade Federal de Sao Carlos, Sao Carlos, SP, Brazil.
authors.forename: Laura M T
authors.initials: LM
authors.lastname: Neves
authors.affiliation: Cardiovascular Physical Therapy Laboratory, Nucleus of Research in Physical Exercise, Universidade Federal de Sao Carlos, Sao Carlos, SP, Brazil.
authors.forename: Marlus
authors.initials: M
authors.lastname: Karsten
authors.affiliation: Cardiovascular Physical Therapy Laboratory, Nucleus of Research in Physical Exercise, Universidade Federal de Sao Carlos, Sao Carlos, SP, Brazil.
authors.forename: Victor R
authors.initials: VR
authors.lastname: Neves
authors.affiliation: Cardiovascular Physical Therapy Laboratory, Nucleus of Research in Physical Exercise, Universidade Federal de Sao Carlos, Sao Carlos, SP, Brazil.
authors.forename: Thomas
authors.initials: T
authors.lastname: Beltrame
authors.affiliation: Cardiovascular Physical Therapy Laboratory, Nucleus of Research in Physical Exercise, Universidade Federal de Sao Carlos, Sao Carlos, SP, Brazil.
authors.forename: Audrey
authors.initials: A
authors.lastname: Borghi-Silva
authors.affiliation: Cardiovascular Physical Therapy Laboratory, Nucleus of Research in Physical Exercise, Universidade Federal de Sao Carlos, Sao Carlos, SP, Brazil.
authors.forename: Aparecida M
authors.initials: AM
authors.lastname: Catai
mesh_terms: D000328:Adult; D000368:Aged; D003430:Cross-Sectional Studies; D005080:Exercise Test; D017079:Exercise Tolerance; D006801:Humans; D008875:Middle Aged; D009203:Myocardial Infarction / Q000503:physiopathology*; D012132:Respiratory Muscles / Q000378:metabolism / Q000502:physiology*