Inclusion Criteria:

• - Age 19 years or older.

• - Idiopathic Pulmonary Fibrosis (IPF) diagnosis according to American Thoracic Society and/or European Respiratory Society consensus criteria.

• - Appropriate candidate for pulmonary rehabilitation.

• - prescribed nintedanib by their treating physician or currently on nintedanib.

• - 6 minute walk distance 50m or more.

• - Oxygen saturation 92% or more by pulse oximetry at rest while breathing room air.

• - Clinically stable for the preceding 6 weeks.

Exclusion Criteria:

• - Contraindication to treatment with nintedanib (based on Canadian labeling) - Contraindication to exercise testing (e.g. significant cardiovascular, musculoskeletal, neurological disease) - Other significant extra-pulmonary disease that, based on clinical assessment, could impair exercise capacity and/or oxygenation.

• - Forced vital capacity (FVC) less than 50% or Diffusion capacity for carbon monoxide (DLCO) less than 25% - Concurrent or recent participation (less than 6 months) in a pulmonary rehabilitation program.

• - Use of prednisone greater than 10 mg/day for more than 2 weeks within 3 months of the first study visit.

• - Use of pirfenidone within 4 weeks of screening.

- Significant emphysema (less than 10% volume on high resolution computed tomography (HRCT) or forced expiratory volume at one second (FEV1)/FVC less than 0.70)

Pulmonary rehabilitation is a structured evidence-based exercise and education intervention that is recommended for most patients with IPF. Pulmonary rehabilitation improves functional capacity (6-minute walk distance [6MWD]), breathlessness and quality of life in patients, however these benefits are often modest and only temporary. Nintedanib is an antifibrotic medication that has been shown to slow the decline of lung function. Use of antifibrotic medications in the pulmonary rehabilitation setting may therefore allow prolonged benefit of exercise training by preventing IPF progression and the resulting worsening symptoms and functional decline. Unpublished data suggest that breathing 60% oxygen in a pulmonary rehabilitation setting could enable patients to train at higher exercise intensities and thus derive greater physiological adaptations and clinical benefits compared with traditional pulmonary rehabilitation. This is a randomized, blinded study with two arms (standard of care or 60% oxygen). The decision to start or stop treatment with nintedanib will be made by the participants treating physician based on clinical findings. If the treating physician decides to discontinue nintedanib, the participant will be allowed to continue in the study. The exercise training program is 8 weeks long, with visits 3 times a week. In addition to the exercise training there are 13 visits occurring before, during and after the 8 week exercise training program. At study visits, participants will be required to conduct a 6 minute walk test and complete a quality of life questionnaire. Select study visits will also require lung function tests and exercise tests to be conducted.

Arms

Experimental: 60% Oxgyen

While participants are exercising, they will be breathing 60% oxygen through a mask.

Placebo Comparator: Standard of Care

While participants are exercising, they will be breathing air through a mask that will be titrated to keep oxygen saturation at least 88%, allowing a maximum inhaled oxygen percentage of 40%.

Interventions

Other: - 60% Oxygen

While participants are exercising, they will be inhaling 60% oxygen through a mask

Other: - Standard of Care

While participants are exercising, they will be breathing air through a mask that will be titrated to keep oxygen saturation at least 88%, allowing a maximum inhaled oxygen percentage of 40%.