title: A protocol to determine valid V˙O2max in young cystic fibrosis patients.
abstract: OBJECTIVE
  Measuring aerobic fitness (V˙O2max) via a maximal cardiopulmonary exercise test is an important clinical tool in cystic fibrosis. This study sought to establish: (1) the validity of traditional criteria to verify maximal efforts during a ramp cardiopulmonary exercise test; and (2) whether V˙O2 measured during an exhaustive cardiopulmonary exercise test represents a valid V˙O2max in paediatric patients, using a subsequent exhaustive supramaximal (Smax) exercise test.
  
  
  METHODS
  Cross-sectional.
  
  
  METHODS
  Fourteen patients (7-18 years; 10 males) completed an exhaustive ramp test to determine V˙O2max. Following 15-min recovery, Smax (110% ramp peak power output) was performed.
  
  
  RESULTS
  Ramp test V˙O2peak was significantly higher than V˙O2 documented at traditional endpoint criteria, including a RER of 1.00 (0.99±0.47 L min(-1) vs. 1.83±0.78 L min(-1), p<0.001) and 1.10 (1.36±0.59 L min(-1) vs. 1.83±0.78 L min(-1), p<0.001), despite 100% of patients satisfying these two criteria. Only 23% and 75% of patients satisfied the 95% age-predicted heart rate (HR) maximum and 180 b min(-1) criteria. Whilst mean ramp and Smax V˙O2peak were not significantly different (1.83±0.78 L min(-1) vs. 1.82±0.67 L min(-1); p=0.88), at the individual level Smax elicited a 'meaningful' (>9%) increase in V˙O2peak (range 9.9-38.3%) compared with V˙O2peak from the ramp test in 3 of 14 cases (21.4%).
  
  
  CONCLUSIONS
  Traditional criteria significantly underestimate V˙O2max in young cystic fibrosis patients. Conversely, Smax can confirm when 'true' V˙O2max is achieved. The use of Smax following cardiopulmonary exercise test represents an appropriate method to measure V˙O2max in young cystic fibrosis patients.
authors.affiliation: Children's Health and Exercise Research Centre, Sport and Health Sciences, University of Exeter, UK; Royal Devon and Exeter NHS Foundation Trust Hospital, UK.
authors.forename: Zoe L
authors.initials: ZL
authors.lastname: Saynor
authors.forename: Alan R
authors.initials: AR
authors.lastname: Barker
authors.forename: Patrick J
authors.initials: PJ
authors.lastname: Oades
authors.forename: Craig A
authors.initials: CA
authors.lastname: Williams
mesh_terms: D000293:Adolescent; D002648:Child; D002985:Clinical Protocols; D003430:Cross-Sectional Studies; D003550:Cystic Fibrosis / Q000378:metabolism*; D005080:Exercise Test / Q000379:methods*; D005260:Female; D006801:Humans; D008297:Male; D010101:Oxygen Consumption
keywords: Cystic fibrosis; Exercise test; Lungs; Paediatric physician; Physical fitness; Supramaximal verification