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Background: Maximal cardiopulmonary exercise testing is recommended on an annual basis for children with cystic fibrosis (CF), due to clinically useful prognostic information provided by maximal oxygen uptake (V̇O 2max ). However, not all patients are able, or willing, to reach V̇O 2max , and therefore submaximal alternatives are required. This study explored the validity of the oxygen uptake efficiency slope (OUES) as a submaximal measure of V̇O 2max in children and adolescents with CF., Methods: Data were collated from 72 cardiopulmonary exercise tests (36 CF, 36 controls), with OUES determined relative to maximal and submaximal parameters of exercise intensity, time, and individual metabolic thresholds. Pearson's correlation coefficients, independent t-tests, and factorial ANOVAs were used to determine validity., Results: Significant (P < 0.05) correlations with V̇O 2max were observed for most expressions of OUES, but were consistently weaker in CF (r = 0.30-0.47) when compared to CON (r = 0.58-0.89). Mean differences for all OUES parameters between groups were not significant (P > 0.05). When split by V̇O 2max tertiles, minimal significant differences were found between, and within, groups for OUES, indicating poor discrimination of V̇O 2max ., Conclusions: The OUES is not a valid (sub) maximal measure of V̇O 2max in children and adolescents with mild-to-moderate CF. Clinicians should continue to use maximal markers (ie, V̇O 2max ) of exercise capacity., (© 2017 Wiley Periodicals, Inc.)

Unlabelled: The clinical importance of exercise testing and training in the healthcare management of young patients with cystic fibrosis (CF) is growing. The aim of the present study was to determine the incidence of airflow limitation following cardiopulmonary exercise testing (CPET) and heavy-intensity intermittent exercise (HIIE) in young patients with CF. Nineteen young patients with CF and respective paired-matched controls performed CPET and HIIE on separate days. Forced expiratory volume in one second (FEV1) was measured pre- and post each exercise modality. A fall in FEV1 of 10 % or greater was used to define airflow limitation. The incidence of airflow limitation was significantly greater in the CF group than in the controls following CPET (32 vs. 5 %; p = 0.03); however, no significant difference in the incidence of airflow limitation was shown following HIIE between the CF group and controls (11 vs. 16 %; p = 0.64)., Conclusion: Our data show that the incidence of airflow limitation following CPET in young patients with CF is high. Therefore, clinicians may wish to identify whether young CF patients experience airflow limitation following strenuous exercise, such as CPET, before it is performed. However, HIIE carries a low risk for airflow limitation and may be prescribed as a safe, yet effective exercise modality for young patients with CF.

Purpose: The purpose of this report was to evaluate the influence of 12 weeks of ivacaftor treatment on the aerobic function of 2 teenage patients with cystic fibrosis (CF; ΔF508/G551D) using a maximal cardiopulmonary exercise test., Summary of Key Points: One patient, with relatively mild disease, demonstrated no clinically meaningful changes in maximal oxygen uptake ((Equation is included in full-text article.)O2max). However, in the second case, with more established lung disease on imaging, (Equation is included in full-text article.)O2max improved by approximately 30%, an improvement out of proportion with early lung function changes. This improvement resulted from increased muscle oxygen delivery and extraction., Statement of Conclusions: Cardiopulmonary exercise testing can monitor the extent and cause(s) of change following interventions such as ivacaftor, with the potential to identify functional changes independent from spirometry indices., Recommendations for Clinical Practice: Cardiopulmonary exercise testing represents an important and comprehensive clinical assessment tool, and its use as an outcome measure in the functional assessment of patients with CF is encouraged.

Background: The reproducibility of cardiopulmonary exercise testing (CPET) has not been established in young cystic fibrosis (CF) patients using a valid protocol., Methods: Thirteen 7-18 year olds completed three CPETs, separated by 48 h and 4-6 weeks. CPET involved a ramp-incremental cycling test with supramaximal verification., Results: Maximal oxygen uptake was repeatedly determined with no learning effect and typical errors expressed as a coefficient of variation (TE(CV%)) of 9.3% (48 h) and 13.3% (4-6 weeks). The reproducibility of additional parameters of aerobic function [gas exchange threshold (TE(CV%): 11.2%, 16.8%); VO2 mean response time (TE(CV%): 37.8%, 89.4%); VO2 gain (TE(CV%): 17.4%, 24.5%)] and clinical utility [e.g. SaO2% (TE(CV%): 2.2%, 3.1%); ventilatory drive (V(E)/VCO2-slope) (TE(CV%): 7.8%, 17.7%)] was also established over the short- and the medium-term, respectively., Conclusion: These results establish limits of variability to determine meaningful changes over the short- and the medium-term for CPET outcomes in young CF patients., (Copyright © 2013 European Cystic Fibrosis Society. Published by Elsevier B.V. All rights reserved.)

Objectives: 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., Design: 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., (Copyright © 2013 Sports Medicine Australia. Published by Elsevier Ltd. All rights reserved.)

Background: Exercise testing is a valuable prognostic tool and exercise training has many health benefits in cystic fibrosis (CF). The objective of this study was to survey the provision of exercise testing and training in UK CF clinics., Methods: A three-page questionnaire was used to determine the extent of, scope and importance assigned to exercise testing and training., Results: Data from returned questionnaires showed that 38.9% of paediatric and 27.8% of adult patients had performed an exercise test in the preceding 12 months, most as part of an annual review process. Pulmonary rehabilitation programmes were accessible in only 31.3% of clinics, and only 26.0% provide exercise training programmes. When assigning importance for exercise testing on a scale from 1 'not important' to 5 'very important', the mean and median respondent scores were 3.5 and 4.0, respectively, and for the importance of training were 4.0 and 4.0, respectively., Conclusions: Despite the level of importance given to exercise testing and training by healthcare providers, exercise is underused as either an assessment tool or therapeutic intervention in the healthcare of patients with CF in the UK., (Copyright © 2010 European Cystic Fibrosis Society. Published by Elsevier B.V. All rights reserved.)