Non-invasive Approaches to Identify the Cause of Fatigue in Inflammatory Bowel Disease Patients.

Crohn's disease (CD) presents with severe symptoms, but fatigue is a very predominant symptom that negatively impacts upon quality of life. Fatigue affects \~40% of patients when well and 80% of patients when the disease is active. It is the second commonest symptom that an IBD patient gets throughout their life-time. The IBD priority-setting partnership between the James Lind Alliance and the British Society of Gastroenterology has recently identified fatigue as an area of unmet clinical need and a priority research field, in which diagnosis and therapeutic intervention are lacking. Based on other diseases that present with fatigue, the cause of fatigue may be divided into peripheral fatigue, mainly driven by anomalies in muscle mass and function and central fatigue, mainly driven through decreased blood supply to the brain during exercise probably due to decreased heart and lung fitness. Research in IBD fatigue until now has been patchy with no convincing evidence that any treatment helps. There has been no research aimed at studying whole body function. It is imperative to have a better understanding of the alterations in muscle, brain, heart and lung function seen in these patients before specific treatments are researched. In this study, the investigators aim to recruit 32 CD patients, half with fatigue and half without. Subjects with active disease or with other known reasons of fatigue will be excluded. Findings in this group will be compared to 16 other healthy control volunteers of a similar age, gender and Body Mass Index. The study aims to recruit all participants over 36 months, and will target people aged from 16 to 60 years of age. Once recruited, the participants will be asked to provide their consent to take-part in 3 experiments on two separate days. These experiments have been designed to carefully consider potential fatigue burden, experimental practicality, and participant availability. Objective 1: The investigators aim to measure muscle fi