title: Relation of exercise capacity with lung volumes before and after 6-minute walk test in subjects with COPD.
abstract: BACKGROUND
  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 FEV1: 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 FEV1. 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 FEV1. 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.
authors.affiliation: Department of Internal Medicine II, University Hospital of Ulm, Ulm, Germany. thomas.wibmer@gmx.de.
authors.forename: Thomas
authors.initials: T
authors.lastname: Wibmer
authors.affiliation: Department of Internal Medicine II, University Hospital of Ulm, Ulm, Germany.
authors.forename: Stefan
authors.initials: S
authors.lastname: Rüdiger
authors.affiliation: Department of Internal Medicine II, University Hospital of Ulm, Ulm, Germany.
authors.forename: Cornelia
authors.initials: C
authors.lastname: Kropf-Sanchen
authors.affiliation: Department of Internal Medicine II, University Hospital of Ulm, Ulm, Germany.
authors.forename: Kathrin M
authors.initials: KM
authors.lastname: Stoiber
authors.affiliation: Department of Internal Medicine II, University Hospital of Ulm, Ulm, Germany.
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Rottbauer
authors.affiliation: Department of Internal Medicine II, University Hospital of Ulm, Ulm, Germany.
authors.forename: Christian
authors.initials: C
authors.lastname: Schumann
mesh_terms: D000368:Aged; D005080:Exercise Test / Q000379:methods*; D017079:Exercise Tolerance / Q000502:physiology*; D005260:Female; D005541:Forced Expiratory Volume / Q000502:physiology; D006801:Humans; D008168:Lung / Q000503:physiopathology*; D008176:Lung Volume Measurements; D008297:Male; D010993:Plethysmography, Whole Body; D029424:Pulmonary Disease, Chronic Obstructive / Q000175:diagnosis / Q000503:physiopathology*; D013990:Tidal Volume / Q000502:physiology*; D016138:Walking / Q000502:physiology*
keywords: body plethysmography; chronic obstructive pulmonary disease; exercise limitation; hyperinflation; pulmonary function