Overall and differentiated sensory responses to cardiopulmonary exercise test in patients with cystic fibrosis: kinetics and ability to predict peak oxygen uptake

Abstract

Purpose

We evaluated the validity of predicting peak oxygen uptake ($\dot {V}$O_2peak) from submaximal ratings of perceived exertion (RPE) during incremental cardiopulmonary exercise test (CPET) in patients with cystic fibrosis (CF) and compared the predictive accuracy between overall and differentiated RPE scores.

Methods

Thirty-five adults with CF (FEV₁ = 58 ± 23%) performed a CPET on cycle ergometer with gas exchange measurements. Leg, chest and overall RPE were collected every minute throughout the test. Linear regressions between $\dot {V}$O₂ and RPE ≤ 15 were extrapolated to maximal theoretical RPE (i.e. RPE₁₈ and RPE₁₉) to predict $\dot {V}$O_2peak. Agreements between measured and all predicted $\dot {V}$O_2peak were tested using Bland–Altman Plots, for the whole group and for subjects presenting significant exercise intolerance (n = 24).

Results

Leg, chest and overall RPE increased similarly with exercise intensity. No differences were found between predicted $\dot {V}$O_2peak and measured $\dot {V}$O_2peak with RPE₁₈ as maximal RPE, for both overall and differentiated RPE (P range 0.94–0.98). Ranges for Pearson correlations and limits of agreements were 0.88–0.91 and 380–461 mL min⁻¹ for the whole group and 0.92–0.94 and 269–365 mL min⁻¹ for subjects with significant exercise intolerance. The greatest association and narrowest limits of agreements were obtained from chest RPE scores.

Conclusions

Submaximal RPE scores obtained during CPET can provide acceptable estimate of $\dot {V}$O_2peak in adults with CF, particularly in those having significant exercise intolerance. Future studies should assess whether the prediction can be improved, particularly by encouraging the regular use of RPE scales during physical activities/exercise rehabilitations sessions.