When symptoms and resting tests disagree in interstitial lung disease: a selective role for cardiopulmonary exercise testing

<title>Extract</title> Exertional dyspnoea is nearly universal in interstitial lung disease (ILD) and remains a major driver of disability and impaired health-related quality of life [1, 2]. Yet one of the most familiar clinical conundrums in ILD is the dissociation between symptom burden and resting assessment. Despite comparable imaging and resting measures, a striking discrepancy exists in how individual patients tolerate the physiological demands of exertion and ordinary daily activity [3, 4]. This gap matters clinically: resting tests help to define disease severity and trajectory, but they do not adequately explain the physiology underlying exertional limitation.