Children and adolescents with inflammatory bowel disease are at increased risk of poor bone and muscle health through a variety of factors, including underlying disease processes, nutritional deficits, and reduced physical activity.

Inflammatory bowel disease can also delay the onset of puberty in children, and pubertal development in adolescents, resulting in sub-optimal adult bone mass, therefore increasing future risk of fractures and osteoporosis. High impact exercise may be a useful additional therapy for adolescents with IBD, as the mechanical strains produced during this type of exercise, through high force muscular contractions and ground reaction forces, can promote bone formation and gains in muscle mass. There have been no previous studies assessing the effects of high impact exercise in IBD, so it is unknown if this type of exercise is feasible in this population. The aim of this study is to assess the feasibility of a short term jumping based exercise intervention for improving muscle and bone outcomes in children and adolescents with inflammatory bowel disease.

This study will incorporate a pilot/feasibility design, aiming to recruit a cohort of 15 inflammatory bowel disease patients of child and adolescent age (10 - 17.9 years). No control group will be recruited.

After potential recruits have contacted the study team to signal their interest in participation, a member of the team will contact them to discuss details of the study in more depth, and assess their suitability for participation against the inclusion/exclusion criteria. If eligible, and willing to participate, they will be asked to attend a baseline session (<28 days prior to exercise intervention) during which they will be afforded the opportunity to ask any questions they may have regarding the study.

This visit will last approximately 1.5 hours. Parent/guardian will also be encouraged to ask any questions they may have. Fully informed written consent with be obtained from the participant's parent/guardian if aged under 16 years, and written informed consent (or assent, depending on competence) will also be taken from the participant. A baseline blood sample will be collected at this session by a research nurse. Participants will complete a range of questionnaires regarding quality of life (IMPACT III, PedsQL Generic Core Scale), fatigue (PedsQL Multidimensional fatigue scale), self-efficacy for exercise. A member of the study team will measure disease activity using a clinical questionnaire (wPCDAI, PUCAI). Demographic and disease history data, and physical measurements including height, sitting height, weight, body composition (bio-electrical impedance) will also be collected. Participants will be provided a wrist-worn accelerometer to measure their habitual physical activity for the proceeding seven days, which they will be instructed to return in a provided pre-paid envelope. A kit will be given for participant to provide a stool sample, to be brought to the following study visit. The exercise intervention will consist of four weeks of three jumping based exercise sessions per week. These sessions will involve basic jumping movements, with approximately 50-100 jumps per session; incorporating 20-30 minutes of exercise. Participants will be requested to attend a one hour face-to-face session at the beginning of each intervention week so a member of the study team can teach them safe and correct execution of each of the prescribed movements for that week. Participants will be provided with an exercise log diary in which they can record adherence to each session, and detail if they have experienced any pain or falls (adverse events), or if anything has prevented them from participating in the prescribed session. Should they be unable to attend any face-to-face session, the exercise diary contains details of the prescribed exercises, and how to perform them. A member of the research team will make telephone contact with research participants and their parent/guardian once per week throughout the four weeks, on any week that they do not attend a face to face exercise session. As a minimum, participants will be expected to attend their first exercise session face-to-face with a member of the research team. Participants will be requested to wear a wrist-worn accelerometer throughout the intervention period, which will be routinely downloaded at each face-to-face session.

Follow-up visits will be completed <14 days post-intervention, at which all of the measurements from the baseline visit will be conducted again (excluding height, habitual physical activity.

Inclusion Criteria:

• confirmed diagnosis of inflammatory bowel disease (Crohn's disease or ulcerative colitis) at least 6 months prior to study involvement
• aged 10 to 17.9 years (inclusive)
• ability to provide written informed consent, or assent with accompanying parent/guardian consent
• ability to mobilise and perform exercise independently
• disease in remission, or mildly/moderately active, according to weighted Paediatric Crohn's disease activity index (wPCDAI) or Paediatric ulcerative colitis activity index (PUCAI)
• stable medication for >4 weeks prior to study, and no planned changes of medication during study period

Exclusion Criteria:

• lack of capacity to provide consent or assent
• pregnancy (females)
• recent (<12 weeks) surgery, or planned surgery during intervention period
• significant contraindication to high-impact exercise
• significant comorbidity
• use of medication known to affect bone turnover (excluding that used to treat IBD [i.e. glucocorticoids])
• BMI > +3.5 standard deviation score (SDS)
• participating in >2 hours per week structured exercise (excluding school physical education)