This study aims to investigate the airway response to exercise and its association with breathlessness in double lung transplant recipients by comparing responses during 5-minute and 15-minute exercise durations.

Participants will undergo a constant workload challenge set at 60% of their peak oxygen uptake in 2 separate sessions: a 5-minute and a 15-minute exercise session, conducted in a random order. Ratings of perceived exertion will be measured every 5 minutes during exercise. Forced expiratory volume in 1 second will be performed before exercise, immediately post-exercise, and at 5, 10, 15, 20, and 30 minutes post-exercise in order to assess the airway response.

Inclusion Criteria:

1. Received double lung transplantation
2. ≥ 3 months post-transplant

Exclusion Criteria:

1. Diagnosis of asthma
2. Significant airflow limitation (≤50% FEV1 predicted)
3. Inability to cooperate with the required tests and measurements
4. Recent infection or rejection within 1 month
5. Exercise contraindication (e.g., recent heart attack or stroke within 3 months, uncontrolled hypertension, known aortic aneurysm, unstable cardiac ischemia, malignant arrhythmias)

double lung transplantation recipients