title: Effects of exercise on respiratory flow and sputum properties in patients with cystic fibrosis.
abstract: BACKGROUND
  The physiologic mechanisms by which exercise may clear secretions in subjects with cystic fibrosis (CF) are unknown. The purpose of this study was to compare ventilation, respiratory flow, and sputum properties following treadmill and cycle exercise with resting breathing (referred to as "control").
  
  
  METHODS
  In 14 adult subjects with CF, ventilation and respiratory flow were measured during 20 min of resting breathing, treadmill exercise, and cycle exercise in a 3-day crossover study. Treadmill and cycle exercise were performed at the work rate equivalent to 60% of the subject's peak oxygen uptake. Ease of expectoration and sputum properties (solids content and mechanical impedance) were measured before and immediately after the interventions and after 20-min recovery.
  
  
  RESULTS
  Ease of expectoration improved following exercise. Ventilation and respiratory flow were significantly higher during treadmill and cycle exercise compared with control. Sputum solids content did not change following treadmill or cycle exercise. There was a significantly greater decrease in sputum mechanical impedance following treadmill exercise compared with control, but no significant decrease in sputum mechanical impedance following cycle exercise compared with control.
  
  
  CONCLUSIONS
  The improvement in ease of expectoration following exercise may have been due to the higher ventilation and respiratory flow. The reductions in sputum mechanical impedance with treadmill exercise may have been due to the trunk oscillations associated with walking.
  
  
  BACKGROUND
  Australian and New Zealand Clinical Trials Registry; No. 12605000422628; URL: www.anzctr.org.au.
authors.affiliation: Discipline of Physiotherapy, Faculty of Health Sciences, University of Sydney, Sydney, NSW, Australia; Department of Respiratory Medicine, Royal Prince Alfred Hospital, University of Sydney, Sydney, NSW, Australia; Central Clinical School, Sydney Medical School, University of Sydney, Sydney, NSW, Australia. Electronic address: tiffany.dwyer@sydney.edu.au.
authors.forename: Tiffany J
authors.initials: TJ
authors.lastname: Dwyer
authors.affiliation: Discipline of Physiotherapy, Faculty of Health Sciences, University of Sydney, Sydney, NSW, Australia; Department of Respiratory Medicine, Royal Prince Alfred Hospital, University of Sydney, Sydney, NSW, Australia.
authors.forename: Jennifer A
authors.initials: JA
authors.lastname: Alison
authors.affiliation: Discipline of Physiotherapy, Faculty of Health Sciences, University of Sydney, Sydney, NSW, Australia.
authors.forename: Zoe J
authors.initials: ZJ
authors.lastname: McKeough
authors.affiliation: Department of Respiratory Medicine, Royal Prince Alfred Hospital, University of Sydney, Sydney, NSW, Australia.
authors.forename: Evangelia
authors.initials: E
authors.lastname: Daviskas
authors.affiliation: Department of Respiratory Medicine, Royal Prince Alfred Hospital, University of Sydney, Sydney, NSW, Australia; Central Clinical School, Sydney Medical School, University of Sydney, Sydney, NSW, Australia.
authors.forename: Peter T P
authors.initials: PTP
authors.lastname: Bye
mesh_terms: D000293:Adolescent; D000328:Adult; D018592:Cross-Over Studies; D003550:Cystic Fibrosis / Q000378:metabolism / Q000503:physiopathology / Q000534:rehabilitation*; D015444:Exercise / Q000502:physiology*; D005081:Exercise Therapy / Q000379:methods*; D005540:Forced Expiratory Flow Rates / Q000502:physiology*; D006801:Humans; D013183:Sputum / Q000378:metabolism*; D055815:Young Adult