title: Exercise performance improves in patients with COPD due to respiratory muscle endurance training.
abstract: BACKGROUND
  Impaired exercise tolerance is frequently observed in patients with COPD. Respiratory muscle endurance training (RMET) by means of normocapnic hyperpnea can be used to improve respiratory muscle function and probably exercise capacity. RMET is not applied on a large scale because complicated equipment is needed to maintain carbon dioxide homeostasis during hyperpnea, which can also be done by enlarging the dead space of the ventilatory system by breathing through a tube. Therefore, tube breathing might be a new, inexpensive method for home-based RMET. The aim of this study was to assess whether home-based RMET by means of tube breathing improves endurance exercise performance in patients with COPD.
  
  
  METHODS
  We randomized 36 patients with moderate-to-severe COPD to RMET by paced tube breathing (n = 18) or sham training (control, n = 18). Both groups trained twice daily for 15 min, 7 days per week, for 5 weeks.
  
  
  RESULTS
  Patients receiving RMET showed significant improvements in endurance exercise capacity (constant-load exercise on cycle ergometry; 18 min vs 28 min, p < 0.001), in perception of dyspnea (Borg score; 8.4 vs 5.4, p < 0.001), and respiratory muscle endurance capacity (sustainable inspiratory pressure; 25 cm H(2)O vs 31 cm H(2)O, p = 0.005). Quality of life (chronic respiratory disease questionnaire) also improved (78.7 to 86.6, p = 0.001). The control group showed no significant changes.
  
  
  CONCLUSIONS
  Home-based RMET by means of tube breathing leads to a significant improvement of endurance exercise capacity, a reduction in perception of dyspnea, and an improvement in quality of life in patients with moderate-to-severe COPD.
authors.affiliation: Medical Center Leeuwarden, PO Box 888, 8901 BR Leeuwarden, The Netherlands. R.J.H.Koppers@ZNB.nl
authors.forename: Ralph J H
authors.initials: RJ
authors.lastname: Koppers
authors.forename: Petra J E
authors.initials: PJ
authors.lastname: Vos
authors.forename: Cecile R L
authors.initials: CR
authors.lastname: Boot
authors.forename: Hans Th M
authors.initials: HT
authors.lastname: Folgering
mesh_terms: D000368:Aged; D001945:Breathing Exercises; D004417:Dyspnea / Q000209:etiology / Q000517:prevention & control; D017079:Exercise Tolerance / Q000502:physiology*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D029424:Pulmonary Disease, Chronic Obstructive / Q000150:complications / Q000503:physiopathology* / Q000534:rehabilitation*; D011788:Quality of Life; D012129:Respiratory Function Tests; D012132:Respiratory Muscles / Q000503:physiopathology; D016896:Treatment Outcome