title: Interval versus continuous high-intensity exercise in chronic obstructive pulmonary disease: a randomized trial.
abstract: BACKGROUND
  Guidelines recommend high-intensity continuous exercise to reduce peripheral muscle dysfunction in patients with chronic obstructive pulmonary disease but acknowledge that interval exercise might be an equally effective alternative that is better tolerated by patients.
  
  
  OBJECTIVE
  To assess whether interval exercise is no less effective than high-intensity continuous exercise and whether it is tolerated better by patients with severe chronic obstructive pulmonary disease.
  
  
  METHODS
  Randomized, noninferiority trial.
  
  
  METHODS
  Publicly funded rehabilitation hospital in Switzerland.
  
  
  METHODS
  98 patients with severe chronic obstructive pulmonary disease, with or without recent exacerbations.
  
  
  METHODS
  12 to 15 supervised interval or high-intensity continuous exercise sessions (over 3 weeks) followed by exercise at home.
  
  
  METHODS
  Health-related quality of life determined by using the Chronic Respiratory Questionnaire (CRQ) (scores from 1 [most severe impairment] to 7 [no impairment]) after 5 weeks and number of unintended breaks during supervised exercise.
  
  
  RESULTS
  Both groups experienced large improvements in health-related quality of life (increase of CRQ total scores of 1.00 [SD, 0.98] for the interval exercise group and 1.02 [SD, 1.05] for the continuous exercise group). Adjusted between-group differences between the interval exercise group and the continuous exercise group (-0.05 [95% CI, -0.42 to -0.32] for CRQ and 1.1 meters [CI, -25.4 to 27.6 meters] for 6-minute walking distance) were within the a priori defined boundaries of noninferiority (0.5 for CRQ and 45 meters for 6-minute walking distance). Twenty-one (47.9%) patients using interval exercise and 11 (24.0%) patients using continuous exercise were able to adhere to the protocol (difference, 23.9 percentage points [CI, 5.0 to 42.8 percentage points]; P = 0.014). The median number of unintended breaks lasting 1 minute or more was 2 (interquartile range, 0 to 16) for patients in the interval exercise group and 11 (interquartile range, 2 to 26) for patients in the continuous exercise group (P = 0.023).
  
  
  CONCLUSIONS
  The study focused on initiation of exercise and not on outpatient or home-based maintenance of exercise.
  
  
  CONCLUSIONS
  Clinicians and patients can choose either of the 2 exercise plans to initiate physical exercise. International Standard Randomized Controlled Trial number: SRCTN11611768.
authors.affiliation: University of Zurich, Zurich, Switzerland. milo.puhan@usz.ch
authors.forename: Milo A
authors.initials: MA
authors.lastname: Puhan
authors.forename: Gilbert
authors.initials: G
authors.lastname: Büsching
authors.forename: Holger J
authors.initials: HJ
authors.lastname: Schünemann
authors.forename: Evelien
authors.initials: E
authors.lastname: VanOort
authors.forename: Christian
authors.initials: C
authors.lastname: Zaugg
authors.forename: Martin
authors.initials: M
authors.lastname: Frey
mesh_terms: D000368:Aged; D001007:Anxiety / Q000209:etiology; D003863:Depression / Q000209:etiology; D005081:Exercise Therapy / Q000379:methods*; D017079:Exercise Tolerance; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D008875:Middle Aged; D029424:Pulmonary Disease, Chronic Obstructive / Q000523:psychology / Q000628:therapy*; D011788:Quality of Life; D016896:Treatment Outcome