A protocol to determine valid in young cystic fibrosis patients

Saynor, Zoe L., Barker, Alan R., Oades, Patrick J. and Williams, Craig A. (2013) A protocol to determine valid in young cystic fibrosis patients. Journal of Science and Medicine in Sport, 16 (6), 539-544. (doi:10.1016/j.jsams.2013.01.010).

Abstract

Objectives: measuring aerobic fitness (VO_2max) 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 the VO₂ measured during an exhaustive cardiopulmonary exercise test represents a valid VO_2max in paediatric patients, using a subsequent exhaustive supramaximal (S_max) exercise test.

Design: cross-sectional.

Methods: fourteen patients (7–18 years; 10 males) completed an exhaustive ramp test to determine VO_2max. Following 15-min recovery, S_max (110% ramp peak power output) was performed.

Results: ramp test VO_2peak was significantly higher than VO₂ 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 S_max VO_2peak 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 S_max elicited a ‘meaningful’ (>9%) increase in VO_2peak (range 9.9–38.3%) compared with VO_2peak from the ramp test in 3 of 14 cases (21.4%).

Conclusions - Traditional criteria significantly underestimate VO_2max in young cystic fibrosis patients. Conversely, S_max can confirm when ‘true’ VO_2max is achieved. The use of Smax following cardiopulmonary exercise test represents an appropriate method to measure VO_2max in young cystic fibrosis patients.

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Contributors

Author: Zoe L. Saynor

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