title: High-intensity inspiratory muscle training in patients with chronic obstructive pulmonary disease and severely reduced function.
abstract: OBJECTIVE
  This study examined the effects of inspiratory muscle training (IMT) with high-intensity inspiratory pressure loads on respiratory muscle performance and exertional dyspnea.
  
  
  METHODS
  This was a randomized single-blind clinical trial. Twenty-seven patients with chronic obstructive pulmonary disease (18 men, 9 women) with severe to very severe airflow obstruction and severely limited functional performance were assigned randomly to an IMT group (n = 12) or an educational control group (n = 15). The IMT group trained with a threshold loaded device for 30 minutes a day for 16 weeks using interval training techniques. Training was initiated with inspiratory pressure loads equal to 30% of maximal inspiratory pressure (Plmax) and increased as tolerated to 60% of Plmax. Dependent variables were measured before and after 4 months of IMT: inspiratory muscle strength (Plmax), respiratory muscle endurance (discontinuous incremental threshold loading test [DC-ITL]), dyspnea (Chronic Respiratory Disease Questionnaire [CRQ]), and the Borg Category-Ratio Scale ratings of perceived breathing difficulty (RPBD) at equal loads during the DC-ITL.
  
  
  RESULTS
  In the IMT group, Plmax increased from 64 +/- 15 to 75 +/- 17 cm H2O (P < .05), performance on the DC-ITL test increased from a maximal load of 37 +/- 12 to 53 +/- 13 cm H2O (P < .05), RPBD decreased from 5.5 +/- 2.5 to 3.8 +/- 2.6 for equal loads on the DC-ITL (P < .05) and the CRQ Dyspnea Scale improved from 18.1 +/- 5.1 to 22.4 +/- 5.2 (P < .05).
  
  
  CONCLUSIONS
  Inspiratory muscle training at high-intensity loads significantly improved inspiratory muscle strength, respiratory muscle endurance, and respiratory symptoms during daily activities and respiratory exertion.
authors.affiliation: University of Illinois at Chicago, College of Nursing, 845 South Damen Avenue, Chicago, IL, USA. mkcovey@uic.edu
authors.forename: M K
authors.initials: MK
authors.lastname: Covey
authors.forename: J L
authors.initials: JL
authors.lastname: Larson
authors.forename: S E
authors.initials: SE
authors.lastname: Wirtz
authors.forename: J K
authors.initials: JK
authors.lastname: Berry
authors.forename: N J
authors.initials: NJ
authors.lastname: Pogue
authors.forename: C G
authors.initials: CG
authors.lastname: Alex
authors.forename: M
authors.initials: M
authors.lastname: Patel
mesh_terms: D000368:Aged; D001945:Breathing Exercises; D004417:Dyspnea / Q000517:prevention & control / Q000628:therapy*; D005260:Female; D006801:Humans; D007320:Inspiratory Capacity; D008173:Lung Diseases, Obstructive / Q000503:physiopathology* / Q000628:therapy*; D008297:Male; D008875:Middle Aged; D012129:Respiratory Function Tests; D012132:Respiratory Muscles / Q000503:physiopathology