title: Feasibility of high-intensity, interval-based respiratory muscle training in COPD.
abstract: BACKGROUND
  Specific respiratory muscle training can improve respiratory muscle function in patients with COPD, but the magnitude of improvement appears dependent on the magnitude of the training load. High training loads are difficult to achieve using conventional, constant loading techniques, but may be possible using interval-based training techniques.
  
  
  METHODS
  To assess the feasibility of high-intensity respiratory muscle training, nine subjects with moderate-to-severe COPD (FEV(1) 34 +/- 12% predicted [mean +/- SD]) completed 8 weeks of interval-based respiratory muscle training combined with a general exercise program. This involved three 20-min sessions per week, each session comprising seven 2-min bouts of breathing against a constant inspiratory threshold load, each bout separated by 1 min of unloaded recovery. Inspiratory load was progressively incremented. Respiratory muscle strength (maximum inspiratory pressure generated against an occluded airway [PImax]) and endurance (maximum pressure generated against a progressively increasing inspiratory threshold load [Pthmax]) were measured before and immediately after the 8-week training period.
  
  
  RESULTS
  By the third training session (week 1), subjects breathed against a threshold that required generation of pressures equivalent to 68 +/- 5% of the pretraining PImax. By week 8, this had increased to 95 +/- 12% of the pretraining PImax. On completion of training, PImax had increased by 32 +/- 27% (p < 0.05), Pthmax had increased by 56 +/- 33% (p < 0.05), and Pthmax/PImax had increased by 20 +/- 20% (p < 0.05).
  
  
  CONCLUSIONS
  This study has demonstrated that high-intensity, interval-based respiratory muscle training is feasible in patients with moderate-to-severe COPD, resulting in significant improvements in respiratory muscle strength and endurance when performed three times a week for 8 weeks.
authors.affiliation: Department of Pulmonary Physiology, Sir Charles Gairdner Hospital, Nedlands, WA, Australia.
authors.forename: Gavin
authors.initials: G
authors.lastname: Sturdy
authors.forename: David
authors.initials: D
authors.lastname: Hillman
authors.forename: Daniel
authors.initials: D
authors.lastname: Green
authors.forename: Sue
authors.initials: S
authors.lastname: Jenkins
authors.forename: Nola
authors.initials: N
authors.lastname: Cecins
authors.forename: Peter
authors.initials: P
authors.lastname: Eastwood
mesh_terms: D000368:Aged; D001945:Breathing Exercises; D005240:Feasibility Studies; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D029424:Pulmonary Disease, Chronic Obstructive / Q000503:physiopathology / Q000534:rehabilitation*; D012119:Respiration; D012132:Respiratory Muscles / Q000503:physiopathology; D012720:Severity of Illness Index