Breathlessness on exertion is a common and troublesome complaint of individuals with
restrictive lung disorders. In these adults, breathlessness contributes to physical
activity-limitation and avoidance and an adverse health-related quality-of-life, often in a
self-perpetuating cycle. It follows that alleviating dyspnea and improving exercise tolerance
are among the principal goals in the management of adults with restrictive lung disorders.
Nevertheless, effective management of breathlessness and physical activity-limitation remains
an elusive goal for many healthcare providers and current therapies (e.g., antifibrotic
agents, oxygen, exercise training) are only partially successful in this regard. Thus,
research aimed at identifying breathlessness-specific medications to complement existing
therapies for the management of physical activity-related breathlessness in restrictive lung
disorders is timely and both clinically and physiologically relevant. The purpose of this
randomized crossover study study is to examine the acute effects of two doses of inhaled
nebulized furosemide (a loop diuretic) on the perception of breathlessness during
laboratory-based cycle exercise in healthy, young men in the presence of an external thoracic
restriction to mimic a 'mild' restrictive lung deficit. To this end, the investigators will
compare the effects of inhaled 0.9% saline placebo and inhaled furosemide (40 mg and 120 mg)
on detailed assessments of breathlessness (sensory intensity and affective responses) and its
physiological determinants (ventilation, breathing pattern, dynamic operating lung volumes,
cardio-metabolic function) symptom-limited, high-intensity, constant-work-rate cycle exercise
testing with external thoracic restriction sufficient to mimic a 'mild' restrictive pulmonary
deficit in healthy, men aged 18-40 years.