This is an interventional double-blind randomized controlled trial, to investigate the short and long-term effects of a supervised exercise training program in patients with IPF, depending on alternate patterns of oxygen supplementation during PR.

The investigators hypothesize that PR service with supplemented oxygen supply regardless of hypoxemia may have significantly better short-term effects in patients with IPF. The study will take place in Corfu General Hospital, by the Departments of Pulmonary Medicine and Physiotherapy and Rehabilitation, respectively. Study participants will be divided in two equal arms 1:1 in a double-blind manner. One of the investigators blinded to their clinical data will assign each participant to PR service either i) with constant supplementary oxygen supply FiO2 50% regardless of saturation status Group A) or ii) without oxygen supply unless upon resting or exercise induced hypoxemia (saturation <88%) (Group B).

Inclusion Criteria:

• diagnosis of IPF based on current established criteria
• no exacerbation previous 3 months
• no participation in such program previous 3 months.
• If on treatment with pirfenidone or nintedanib, this will be recorded and patient should be on treatment for at least 3-6 months to achieve stable state.

Exclusion Criteria:

- concomitant diagnosis of congestive heart failure and lung cancer.

Everything will be published in time.

participants are blindly randomized to receive oxygen or not during rehabilitation.