 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. 