Idiopathic pulmonary fibrosis (IPF) is a disease characterised with significant morbidity and poor prognosis. Dyspnoea and impaired exercise capacity are very common manifestations of the disease, and result in significant impairment of patients' quality of life. Although hypoxemia is common among subjects with IPF, published data on the effects of supplementary oxygen therapy on specific clinical outcomes among these patients are currently few, while the existing data on the potential benefits of oxygen supplementation to treat exercise-induced hypoxemia, in this patient population, are even more controversial.

Based on the aforementioned, the purpose of this prospective, cross-over clinical trial is to investigate the acute effects of supplemental oxygen administration on the: a) exercise capacity, b) severity of dyspnea, c) cerebral oxygenation, b) muscle oxygenation, and e) hemodynamic profile, as compared to delivery of medical air (sham oxygen), in a group of patients with IPF, without resting hypoxemia, during steady state cardiopulmonary exercise testing (CPET).

Inclusion Criteria:

• Stable IPF patients with no hospitalization, exacerbation or change in regular IPF medication during the last month
• IPF patients do not present with resting hypoxemia, but manifest exercise induced hypoxemia

Exclusion Criteria:

1. Major contraindications for CPET conduction
2. Not provision of informed consent -