title: Prolonged Oxygen Kinetics During Constant Workload Submaximal Exercise Is Associated With Disease Severity in Adult Subjects With Cystic Fibrosis.
abstract: BACKGROUND
  The goal of this study was to explore the relation between oxygen kinetics during constant work load submaximal cardiopulmonary exercise test (CPET) and disease severity in adult subjects with cystic fibrosis.
  
  
  METHODS
  Fourteen adult subjects with cystic fibrosis (CF; 8 males, 22 ± 4 y old) and a mean Schwachman score of 73 ± 11 and 10 healthy individuals (5 males, 29 ± 4 y old) underwent pulmonary function tests at rest, maximal and constant work load submaximal CPET on a cycloergometer. Breath-by-breath analysis was used for measuring oxygen kinetic parameters and the time constant (tau), expressing phase 2 of submaximal CPET.
  
  
  RESULTS
  Subjects with CF had a significantly prolonged tau compared with healthy subjects (42.3 ± 21.5 vs. 29.3 ± 6.4, s, P < .05). The tau during phase 2 was inversely correlated with FEV1(% pred) (r = -0.77, P = .001), breathing reserve (r = -0.74, P = .003), V̇O2peak (r = -0.53, P = .049), V̇O2/t slope (r = -0.58, P = .03), and Schwachman score (r = -0.80, P = .001). In a multivariate regression model including all the above variables, the Schwachman score (β = -0.697, P = .002) emerged as independent predictor of tau (R2 = 0.719, P = .001).
  
  
  CONCLUSIONS
  We conclude that adult subjects with CF present significant prolonged oxygen kinetics during constant work load submaximal exercise in relation to disease severity. Thus, submaximal exercise should be considered the preferable CPET choice in adult patients with severe CF.
authors.affiliation: 10th Pulmonary Department, Athens Chest Hospital, Athens, Greece.
authors.forename: Eleni
authors.initials: E
authors.lastname: Armeniakou
authors.affiliation: 10th Pulmonary Department, Athens Chest Hospital, Athens, Greece.
authors.forename: Georgia
authors.initials: G
authors.lastname: Perpati
authors.affiliation: 1st Critical Care Medicine Department, Cardiopulmonary Exercise Testing and Rehabilitation Laboratory, Evgenidio Hospital, National and Kapodistrian University of Athens, Athens, Greece.
authors.forename: Stavros
authors.initials: S
authors.lastname: Dimopoulos
authors.affiliation: 1st Critical Care Medicine Department, Cardiopulmonary Exercise Testing and Rehabilitation Laboratory, Evgenidio Hospital, National and Kapodistrian University of Athens, Athens, Greece.
authors.forename: Petros
authors.initials: P
authors.lastname: Roditis
authors.affiliation: 10th Pulmonary Department, Athens Chest Hospital, Athens, Greece.
authors.forename: Maria
authors.initials: M
authors.lastname: Avdikou
authors.affiliation: 10th Pulmonary Department, Athens Chest Hospital, Athens, Greece.
authors.forename: Nikolaos
authors.initials: N
authors.lastname: Barouchos
authors.affiliation: 10th Pulmonary Department, Athens Chest Hospital, Athens, Greece.
authors.forename: Vasiliki
authors.initials: V
authors.lastname: Dionisopoulou
authors.affiliation: 1st Critical Care Medicine Department, Cardiopulmonary Exercise Testing and Rehabilitation Laboratory, Evgenidio Hospital, National and Kapodistrian University of Athens, Athens, Greece. a.icusn@gmail.com.
authors.forename: Serafim
authors.initials: S
authors.lastname: Nanas
mesh_terms: D000328:Adult; D001944:Breath Tests / Q000379:methods; D003550:Cystic Fibrosis / Q000503:physiopathology*; D015444:Exercise / Q000502:physiology*; D005080:Exercise Test / Q000706:statistics & numerical data; D017079:Exercise Tolerance / Q000502:physiology*; D005260:Female; D064368:Healthy Volunteers; D006801:Humans; D008297:Male; D010101:Oxygen Consumption / Q000502:physiology; D010366:Peak Expiratory Flow Rate; D055070:Resistance Training / Q000379:methods*; D012119:Respiration; D012720:Severity of Illness Index; D055815:Young Adult
keywords: cystic fibrosis; submaximal exercise; time constant (tau)