Chest
Volume 139, Issue 4, April 2011, Pages 870-877
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Original Research
Cystic Fibrosis
Effects of Exercise on Respiratory Flow and Sputum Properties in Patients With Cystic Fibrosis

https://doi.org/10.1378/chest.10-1158Get rights and content

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.

Trial Registry

Australian and New Zealand Clinical Trials Registry; No. 12605000422628; URL: www.anzctr.org.au

Section snippets

Subjects

Adults with CF were recruited from the CF Clinic at Royal Prince Alfred Hospital in Sydney, New South Wales, Australia. Subjects were excluded if they had received a lung transplantation, were infected with Burkholderia cepacia complex, or were not clinically stable. Research procedures were approved by the Sydney South West Area Health Service Ethics Committee (Protocol X-05-0020), and subjects provided written informed consent prior to participation.

Study Design

Subjects participated in a 3-day crossover

Results

Fifteen subjects with CF were recruited, and 14 completed the study. Participant baseline characteristics are presented in Table 1, Table 2. One participant withdrew after the first visit because of a respiratory exacerbation. Results for this subject on the first day were similar to those of the other 14 but have not been included in the analyses because of the crossover design of the study.

There were no significant differences in preintervention ease of expectoration or sputum properties on

Discussion

The primary purpose of this study was to determine the effects of treadmill and cycle exercise on mechanisms of mucus clearance in CF. To our knowledge, this study is the first to examine the in vivo changes in sputum properties and airflow bias (PEF:PIF) with exercise in CF. The main finding was the reduction in sputum mechanical impedance with treadmill exercise compared with control.

Ventilation and respiratory flow were higher during treadmill and cycle exercise compared with control. The

Acknowledgments

Author contributions: Dr Dwyer: contributed to the study design, data collection, measurement and analysis of sputum properties, interpretation of the findings, and writing of the manuscript.

Dr Alison: contributed to the study design, interpretation of the findings, and writing of the manuscript.

Dr McKeough: contributed to the study design, data collection, interpretation of the findings, and writing of the manuscript.

Dr Daviskas: contributed to the study design, measurement and analysis of

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    Reproduction of this article is prohibited without written permission from the American College of Chest Physicians (http://www.chestpubs.org/site/misc/reprints.xhtml).

    Funding/Support: Dr Dwyer was supported by an Australian Postgraduate Award scholarship from the University of Sydney. No other funding was received for this work.

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