Exercise and large airway issues

Abstract

The large airways, extending from the trachea to the main bronchi, respond dynamically to exercise-induced ventilatory demands. Large airway collapse (LAC) represents a spectrum of conditions characterized by excessive reduction in tracheal and/or main bronchial lumen during expiration. Utilizing the most common diagnostic criteria, defined as ≥50% reduction in airway cross-sectional area during expiration, LAC is a common finding in around one in three patients with underlying lung disease. However, it is also apparent that healthy, asymptomatic people meet this diagnostic criteria. Despite being recognized as a cause of exertional symptoms, the relationship between LAC and exercise-related symptoms or limitation is currently poorly understood. Traditional clinical approaches use forced expiratory measurements performed at rest during bronchoscopy or imaging studies to assess the condition. But novel tests, visualizing the large airways during exercise, may provide more physiologically relevant insight and are an important next step towards the development of targeted interventions for this clinical entity. This review aims to examine large airway behavior during different ventilatory challenges, with particular focus on comparing exercise hyperpnea with forced expiratory maneuvers.

Keywords: excessive dynamic airway collapse; exercise; large airway; tracheobronchomalacia.

FIGURE 1

(a) Trachea and main bronchi. (b) Classification of large airway collapse by cross‐sectional airway morphology, with some associated causes. Reprinted with permission of the American Thoracic Society. Copyright © 2025 American Thoracic Society. All rights reserved (Housley et al., 2024).

FIGURE 2

Axial CT imaging of a 53‐year‐old female. (a) End inspiratory CT image of the trachea displaying a round, circular shape, with a cross‐sectional area of 2.8 cm². (b) End expiratory image at a similar tracheal level displaying a bowing, crescent shape flattening of the posterior membrane. Cross‐sectional area decreased to 0.41 cm², an 85% reduction.

FIGURE 3

Continuous bronchoscopy during exercise (CBE) assessment of a 25‐year‐old female participant. (1) Experienced pulmonologist reviewing airway images. (2) Participant exercising with bronchoscope in‐situ. (3) Exercise physiologist recording vital sign measures and ratings of perceived exertion.