title: COPD patients' oxygen uptake and heart rate on-kinetics at cycle-ergometer: correlation with their predictors of severity.
abstract: OBJECTIVE
  To assess whether there is a correlation between oxygen uptake (VO2) and heart rate (HR) on-kinetics in the constant-load cycle-ergometer test (CLT) and the BODE index and its isolated variables in patients with chronic obstructive pulmonary disease (COPD).
  
  
  METHODS
  Fourteen male patients between 55 and 78 years of age with moderate to severe COPD were evaluated. Each patient underwent spirometry, the six-minute walk test (6MWT), the cycle-ergometer incremental test (IT) and CLT on alternate days. The exhaled gases were collected, and the VO2 and HR on-kinetics were analyzed. The BODE index was calculated.
  
  
  RESULTS
  It was noted that the VO2 tau (τ) and mean response time (MRT) were significantly higher than HR τ and MRT. Moderate and strong correlations between τ and MRT of the VO2 and HR and the BODE index was noted (r=0.75 and r=0.78; r=0.62 and r=0.63, respectively), and there were correlations between the VO2 τ and MRT and the forced expiratory volume in one second (FEV1) (r=-0.60; r=-0.53) and the distance traveled at 6MWT (DT-6MWT) (r=-0.61; r=-0.44) and DT-6MWT % predicted (r=-0.62; r=-0.46). The HR τ and MRT were correlated with DT-6MWT (r=-0.59; r=-0.58) and DT-6MWT % predicted (r=-0.62; r=-0.62).
  
  
  CONCLUSIONS
  The slowing of cycle-ergometer VO2, and especially of HR on-kinetics, may be key markers of disease severity. Furthermore, airflow obstruction and reduced exercise capacity are associated with the slowing of patients' VO2 and HR on-kinetics.
authors.affiliation: Spirometry and Respiratory Therapy Laboratory, Universidade Federal de São Carlos (UFSCar), São Carlos, SP, Brazil. brunavpessoa@hotmail.com
authors.forename: Bruna V
authors.initials: BV
authors.lastname: Pessoa
authors.forename: Thomas
authors.initials: T
authors.lastname: Beltrame
authors.forename: Valéria A Pires
authors.initials: VA
authors.lastname: Di Lorenzo
authors.forename: Aparecida M
authors.initials: AM
authors.lastname: Catai
authors.forename: Audrey
authors.initials: A
authors.lastname: Borghi-Silva
authors.forename: Mauricio
authors.initials: M
authors.lastname: Jamami
mesh_terms: D000368:Aged; D005080:Exercise Test; D006339:Heart Rate; D006801:Humans; D008297:Male; D008875:Middle Aged; D010100:Oxygen / Q000378:metabolism*; D029424:Pulmonary Disease, Chronic Obstructive / Q000378:metabolism* / Q000503:physiopathology*; D012720:Severity of Illness Index
chemical_list: D010100:Oxygen