title: Validity of the oxygen uptake efficiency slope in children with cystic fibrosis and mild-to-moderate airflow obstruction.
abstract: OBJECTIVE
  The oxygen uptake efficiency slope (OUES) has been proposed as an 'effort-independent' measure of cardiopulmonary exercise capacity, which could be used as an alternative measurement for peak oxygen uptake (VO(2peak)) in populations unable or unwilling to perform maximal exercise. The aim of the current study was to investigate the validity of the OUES in children with cystic fibrosis (CF).
  
  
  METHODS
  Exercise data of 22 children with CF and mild to moderate airflow obstruction were analyzed and compared with exercise data of 22 healthy children. The OUES was calculated using data up to three different relative exercise intensities, namely 50%, 75%, and 100% of the total exercise duration, and normalized for body surface area (BSA).
  
  
  RESULTS
  Only the OUES/BSA using the first 50% of the total exercise duration was significantly different between the groups. OUES/BSA values determined at different exercise intensities differed significantly within patients with CF and correlated only moderately with VO(2peak) and the ventilatory threshold.
  
  
  CONCLUSIONS
  The OUES is not a valid submaximal measure of cardiopulmonary exercise capacity in children with mild to moderate CF, due to its limited distinguishing properties, its nonlinearity throughout progressive exercise, and its moderate correlation with VO(2peak) and the ventilatory threshold.
authors.affiliation: Wilhelmina Children's Hospital, University Medical Center Utrecht, Utrecht, The Netherlands.
authors.forename: Bart C
authors.initials: BC
authors.lastname: Bongers
authors.forename: Erik H J
authors.initials: EH
authors.lastname: Hulzebos
authors.forename: B G M
authors.initials: BG
authors.lastname: Arets
authors.forename: Tim
authors.initials: T
authors.lastname: Takken
mesh_terms: D000293:Adolescent; D000704:Analysis of Variance; D016022:Case-Control Studies; D002648:Child; D002669:Child Welfare; D003550:Cystic Fibrosis / Q000378:metabolism / Q000473:pathology*; D005080:Exercise Test; D017079:Exercise Tolerance / Q000502:physiology*; D005260:Female; D006801:Humans; D008297:Male; D010101:Oxygen Consumption / Q000502:physiology; D010809:Physical Fitness / Q000502:physiology; D011237:Predictive Value of Tests; D029424:Pulmonary Disease, Chronic Obstructive / Q000378:metabolism / Q000473:pathology*; D015203:Reproducibility of Results; D012129:Respiratory Function Tests; D013223:Statistics as Topic