It is estimated that one in every 3,600 children in Canada has cystic fibrosis (CF). CF is a
genetic disease that affects the glands that produce mucus and sweat. In CF, mucus production
increases and the mucus becomes thick and sticky. This can block the airways, making it
difficult to breathe. Mucus production also causes bacteria to grow, which can lead to
infections in the lungs. Individuals with CF suffer from shortness of breath, wheezing,
cough, and poor exercise capacity. There are limited treatment options to reduce shortness of
breath in these individuals. Some medications known as bronchodilators are commonly
prescribed to reduce breathlessness in patients with CF. These drugs help open the airways
making it easier to breathe. Unfortunately, there is limited scientific proof that these
drugs can reduce shortness of breath and improve exercise capacity in patients with CF. As a
result, some experts have recommended that these drugs should not be prescribed for patients
with CF. The purpose of this study is to examine the effects of a bronchodilator on shortness
of breath, exercise performance, and breathing responses compared to a placebo drug in adults
with CF.