Causer AJ; Shute JK; Cummings MH; Shepherd AI; Bright V; Connett G; Allenby MI; Carroll MP; Daniels T; Saynor ZL;

Journal Of Applied Physiology (Bethesda, Md.: 1985) [J Appl Physiol (1985)] 2018 Aug 02. Date of Electronic Publication: 2018 Aug 02.

Introduction: The validity and safety of using supramaximal verification (Smax) to confirm a maximal effort during cardiopulmonary exercise testing (CPET) in people with cystic fibrosis (CF) and/or those with severe disease has been questioned. Therefore, this study aimed to investigate these concerns in children, adolescents and adults with mild-to-severe CF lung disease.
Methods: Retrospective analysis of 17 pediatric and 28 adult participants with CF (age range: 9.2-62.9 y; forced expiratory volume in 1 s: 66.7% [range: 29.9-102.3%]; 30 males) who completed a routine ramp incremental cycling test to determine peak oxygen uptake (V̇O2peak). Maximal oxygen uptake (V̇O2max) was subsequently confirmed by Smax at 110% of peak power output.
Results: All participants satisfied the criteria to verify a maximal effort during CPET. However, Smax-V̇O2peak exceeded ramp-V̇O2peak in 3/14 (21.4%) of pediatric and 6/28 (21.4%) adult exercise tests. A valid measurement of V̇O2max was attained in 85.7% of pediatric and 96.4% of adult exercise tests, as Smax-V̇O2peak did not exceed ramp-V̇O2peak by > 9%. Nine adults experienced a {greater than or equal to} 5% reduction in arterial O2 saturation during CPET; 4 during both the ramp and Smax, 3 during only the ramp and 2 during Smax only. Smax did not significantly worsen perceived breathing effort, chest tightness, throat narrowing or exertion compared with ramp incremental testing.
Conclusions: Given the clinical importance of aerobic fitness in people with CF, incorporating Smax is recommended to provide a safe and valid measure of V̇O2max in children, adolescents and adults who span the spectrum of CF disease severity.