Relation of Exercise Capacity With Lung Volumes Before and After 6-Minute Walk Test in Subjects With COPD

Abstract

INTRODUCTION:There is growing evidence that exercise-induced variation in lung volumes is an important source of ventilatory limitation and is linked to exercise intolerance in COPD. The aim of this study was to compare the correlations of walk distance and lung volumes measured before and after a 6-min walk test (6MWT) in subjects with COPD. METHODS: Forty-five subjects with stable COPD (mean pre-bronchodilator FEV 1 : 47 ؎ 18% predicted) underwent a 6MWT. Body plethysmography was performed immediately pre-and post-6MWT. RESULTS: Correlations were generally stronger between 6-min walk distance and post-6MWT lung volumes than between 6-min walk distance and pre-6MWT lung volumes, except for FEV 1 . These differences in Pearson correlation coefficients were significant for residual volume expressed as percent of total lung capacity (؊0.67 vs ؊0.58, P ‫؍‬ .043), percent of predicted residual volume expressed as percent of total lung capacity (؊0.68 vs ؊0.59, P ‫؍‬ .026), inspiratory vital capacity (0.65 vs 0.54, P ‫؍‬ .019), percent of predicted inspiratory vital capacity (0.49 vs 0.38, P ‫؍‬ .037), and percent of predicted functional residual capacity (؊0.62 vs ؊0.47, P ‫؍‬ .023). CONCLUSIONS: In subjects with stable COPD, lung volumes measured immediately after 6MWT are more closely related to exercise limitation than baseline lung volumes measured before 6MWT, except for FEV 1 . Therefore, pulmonary function testing immediately after exercise should be included in future studies on COPD for the assessment of exercise-induced ventilatory constraints to physical performance that cannot be adequately assessed from baseline pulmonary function testing at rest.

Relationship between exercise endurance and static hyperinflation in a post hoc analysis of two clinical trials in patients with COPD

“…While the relationship between hyperinflation and exercise endurance is subject to considerable debate, 1 , 17 the lack of evidence to suggest a correlation observed here supports the theory that static hyperinflation, while important in predicting patient outcomes in COPD, is not as important as dynamic hyperinflation in predicting improvement in exercise capacity. 17 , 34 , 35 The lack of dynamic hyperinflation data is a limitation of this study; these data are technically challenging to obtain using the ESWT, due to the difficulty of performing spirometry measurements during exercise. However, measurement of lung volume during exercise should be prioritized in future studies.…”

“… 14 – 16 It has been established that exercise intolerance in COPD is related to lung hyperinflation; however, the precise relationship is complicated, partly due to debate over the relative contributions of dynamic and static hyperinflation. 1 , 8 , 17 Other factors may also play a role: exercise limitation reflects a complex interaction of ventilatory, cardiovascular, metabolic, muscular, and psychological factors, with variable relative contributions between individuals. 8 , 17 …”

“… 1 , 8 , 17 Other factors may also play a role: exercise limitation reflects a complex interaction of ventilatory, cardiovascular, metabolic, muscular, and psychological factors, with variable relative contributions between individuals. 8 , 17 …”

Static hyperinflation is associated with ventilatory limitation and exercise tolerance in adult cystic fibrosis

“…26 Previous studies in chronic obstructive pulmonary disease have reported that hyperinflation of the lung is related to exercise tolerance; however, the precise contribution made by static or dynamic hyperinflation is still unclear. 12,27,28 The relationship between static and dynamic hyperinflation and their relative contributions to exercise tolerance have, as of yet, not been investigated in cystic fibrosis. The present study showed a significant moderate correlation between static hyperinflation (RV/TLC) and dynamic hyperinflation.…”

Effects of umeclidinium/vilanterol on exercise endurance in COPD: a randomised study

“…Why the marked and sustained improvements in lung hyperinflation did not translate into improvements in EET is unclear, but may be due to the complex and multifactorial processes involved in walking. It has previously been reported that static hyperinflation is less useful than dynamic hyperinflation in predicting improvements in exercise tolerance [ 20 , 22 , 23 ]. In this study, the large ICC at each study site indicated a high degree of similarity in EET measurements between the run-in period and randomisation visits.…”