This study is investigating the reliability of the 4 metre gait speed test (4MGS) in patients with a lung disease called Idiopathic Pulmonary Fibrosis (IPF).

This observational study is investigating a simple test of walking speed, measured using the 4 metre gait speed test (4MGS), in patients with a lung disease called Idiopathic Pulmonary Fibrosis (IPF). Drug development for this disease is slow in part because there is a lack of reliable measurements that can assess effectiveness of treatment. Slow walking speed has been shown to relate to poor outcomes in older adults and people with another lung disease called Chronic Obstructive Pulmonary Disease (COPD. The investigators are interested to see whether usual walking speed is a reliable measure in patients with IPF as this will help inform us of its potential use as an outcome measure. To do this, participants who consent to taking part in the study will be timed walking at their usual walking speed over a distance of 4 metres (13.12 feet). Participants will be asked to do this twice with a rest in between if required. One week later, participants will be asked to repeat the walking tests again.

Inclusion Criteria:

• IPF diagnosis according to NICE guidelines
• Provision of informed consent

Exclusion Criteria:

• Significant co-morbidities that would limit walking ability, exercise capacity or make exercise unsafe (e.g. unstable ischaemic heart disease, neuromuscular disease, severe hip/lower limb joint pain, peripheral vascular disease, lower limb amputation)
• Any patient whom the chief investigator feels it is unsafe to exercise (e.g. unstable cardiovascular disease)
• Any condition that precludes providing informed consent e.g. cognitive impairment or poor English

Patients diagnosed with IPF according to NICE guidelines