Large airway collapse on expiration is an increasingly recognized cause of airway centric symptoms. The 2 primary conditions are tracheobronchomalacia and excessive dynamic airway collapse, the latter a common comorbidity in those with underlying lung disease. The exertional dyspnea associated with these conditions is complex and exercise intolerance is a key clinical feature, despite the fact that the precise relationship is not fully understood. Forced expiratory maneuvers during supine bronchoscopy or imaging studies are used to evaluate these conditions. However, it may be relevant to characterize large airway function during occasions when patients present their symptoms.