The bronchodilators (BD) have been widely used in bronchiectasis (BCE) therapeutic and have been shown to be effective in improving exercise capacity in patients with chronic obstructive pulmonary disease and asthma. However the BD effect on the exercise capacity of patients with BCE is poorly known. Besides, the respiratory mechanics pattern of the patients with BCE is not known nor its association with their physical activity level (PAL). Therefore, the hypothesis of this study is that BD are effective in improving exercise capacity of patients with BCE. The authors also propose to characterize the respiratory mechanics of the patients with BCE and to evaluate their PAL and its association with quality of life, as secondary aims.

This is a randomized, double-blind, crossover, placebo-controlled trial. Forty clinically stable patients with bronchiectasis (BCE), all sexes, 18 to 59 years, will be evaluated in two non-consecutive days. On the first day, anamnesis, anthropometric evaluation and lung function will be performed, followed by: Quality of Life Questionnaire-Bronchiectasis, Saint George questionnaire, modified Medical Research Council scale and social and economic status. Then, a cardiopulmonary exercise test (CPET) will be performed and after a rest period, a bronchodilator (BD) or placebo randomization will precede a constant load exercise test (CLET) with the respiratory mechanics assessment (OEP). Spirometry will be performed pre and post BD/placebo. Finally, the accelerometer will be coupled to the patient for 7 consecutive days, aiming to assess the PAL. On the second day, after at least one-week washout, the accelerometer will be collected and the patient will repeat the CLET with the respiratory mechanics assessment, at the opposite condition to the randomization. The randomization sequence will be generated by computer, and put in sealed and opaque envelopes by a volunteer not involved in the study. The BD or placebo will be administered by a volunteer not involved in the study, according to the randomization. The evaluator will not have access to information on which intervention (BD or placebo) was given prior to each CLET. A paired (anthropometric and social and economic status) healthy control group will be assessed by spirometry, CPET, and CLET and OEP, for comparing respiratory mechanics. In addition the participants will also use an accelerometer for 7 consecutive days. Data of endurance time from CLET, respiratory mechanics from OEP, dyspnea and vital signs will be assessed before and after both BD and placebo CLET. Data about onset of BCE, comorbidities and BCE medication will be collected from the patient's medical record. Data normality will be tested by Kolmogorov-Smirnov. Data comparison will be performed by t test or Wilcoxon and the association by Pearson or Spearman. Categorical data will be analyzed by qui-square test or Fischer. The significance level will be set to 5% for all tests.

Inclusion Criteria:

• All sexes
• 18 to 59 years
• Bronchiectasis diagnosis, according to thorax the Computed Tomography (Pasteur et al., 2010)
• Clinically stable (last 30 days without exacerbation/hospitalization)
• Air trapping on plethysmography (Residual Volume/Total Lung Capacity>125%)
• Smoking Load <10 pack-years

Exclusion Criteria:

• Do not accept to participate
• Smoking
• Continuous oxygen use
• Pulmonary Rehabilitation program in the last 6 months
• Previous lung resection
• Uncontrolled cardiovascular disease
• Other respiratory chronic diseases
• Neurological or musculoskeletal disorders that limit exercise
• Cognitive deficits that limit comprehension

All the measurements will be performed by a blinded professional, who will be masked from randomization and other results. The randomization sequence will be generated by computer, and put in sealed and opaque envelopes by a volunteer not involved in the study. The bronchodilator (BD) or placebo will be administered by a professional not involved in the study, according to the randomization. The evaluator will not have access to information on which intervention (BD or placebo) was given prior to each CLET.