In this single centre non-randomised pilot cohort study we wish to quantify the effect of a twice weekly, 8 week, structured responsive exercise training programme on exercise tolerance, symptoms and health related quality of life in patients with Idiopathic Pulmonary Fibrosis (IPF). We also wish to assess the effect of exercise training on fibrotic processes causing IPF through measurement of blood biomarkers of disease activity.

Idiopathic pulmonary fibrosis (IPF) is a progressive fibrotic lung disease characterised by progressive exercise intolerance and breathlessness. In 2012 there were 32 500 people living in the United Kingdom (UK) with IPF. Average life expectancy from time of diagnosis is 2-3 years (Ley et al. 2011). Despite recent advances in drug therapy, therapeutic options are limited and no medication has been found to halt progression of the disease. Pulmonary Rehabilitation (PR) is a structured exercise and education intervention that is well established as a core treatment intervention for patients with Chronic Obstructive Pulmonary Disease (COPD). Current limited evidence shows that PR is safe in patients with IPF and can lead to short-term improvements in exercise tolerance, symptoms and quality of life (Dowman et al. 2014). However the optimal exercise protocol, the longer-term benefits and which group or patients (those with milder or more severe disease) benefit most is unclear. Further it is unknown what mechanisms underlie any improvement and whether exercise training influences the fibrotic process causing IPF.

Inclusion Criteria:

• Participants aged 18-85 years with a confirmed diagnosis of fibrotic interstitial lung disease (fILD) including; Usual Interstitial Pneumonia, fibrotic Nonspecific interstitial pneumonia (NSIP), Chronic hypersensitivity pneumonitis (chronic HP) and unclassifiable interstitial lung disease (unclassified ILD). Medical Research Council (MRC) breathlessness scale grade 1-3. Clinically stable for 3 months as judged by investigator

Exclusion Criteria:

• Forced Expiratory Volume in 1 second (FEV1) to Forced Vital Capacity (FVC) FEV1/FVC ratio <0.7
• Patients with severe heart failure New York Heart Association (NYHA) grade III or IV or left ventricular systolic function <45%
• Current use of ambulatory or long term oxygen therapy
• Resting oxygen saturations <85% on air
• The presence of infection or exacerbation requiring hospitalization, within 3 months prior to recruitment
• Commencement on anti-fibrotic therapy (Pirfenidone® or Nintedanib®) within 3 months prior to recruitment to the study
• Patients taking oral corticosteroids: unless the dose is less than 15 mg of prednisolone or equivalent, and the dose has been stable for 8 weeks at the time of booking
• Neoplastic disease undergoing treatment or active follow-up
• Current or previous history of sarcoidosis or collagen vascular disease
• Any condition which would prevent completion of cycle-ergometer testing, Pulmonary Function Tests (PFTs) or 6 minute walk test (6-MWT) as judged by the investigator.
• Participation in a Pulmonary Rehabilitation (PR) program in the last 6 months
• Any condition excluding Cardiopulmonary Exercise Testing (CPET) based on the absolute contraindication as the American College of Chest Physicians (ACCP)/ American Thoracic Society (ATS) guidelines 2003 listed here: History of exercise induced syncope, Uncontrolled arrhythmia causing symptoms or hemodynamic compromise, Syncope, Acute endocarditis, Acute myocarditis or pericarditis, Symptomatic severe aortic stenosis, Uncontrolled heart failure, History of acute venous thrombo-embolism, Suspected dissecting aneurysm, uncontrolled asthma, Pulmonary oedema, Mental impairment leading in ability to cooperate, Room air desaturation to <85% unless supplemental O2 is provided for exercise, Acute non-cardiopulmonary disorder that may affect exercise performance/ aggravated by exercise
• Positive Pregnancy test in females of childbearing age.