# High-intensity interval training and moderate-intensity continuous training in adults with Crohn's disease: a pilot randomised controlled trial PMID: 30696423 Journal: BMC gastroenterology Published: 2019 Jan 29 Authors: Tew GA, Leighton D, Carpenter R, Anderson S, Langmead L, Ramage J, Faulkner J, Coleman E, Fairhurst C, Seed M, Bottoms L ## Question Can supervised HIIT or MICT be feasibly and acceptably delivered to adults with quiescent or mildly active Crohn's disease, and what preliminary benefits and harms are observed? ## Summary This pilot randomized controlled trial tested whether supervised cycle-based HIIT and moderate continuous cycling were feasible, acceptable, and apparently safe for adults with quiescent or mildly active Crohn's disease. Thirty-six participants were randomized to HIIT, MICT, or usual care. Both exercise programs were generally acceptable, attendance and outcome completion were adequate for planning a larger trial, and peak oxygen uptake improved more after HIIT than MICT relative to control. Three non-serious exercise-related adverse events occurred, and two exercise participants had disease relapse during follow-up, with authors judging those relapses more likely related to disease course or medication change than exercise. ## Population - Adults and older adolescents with quiescent or mildly active Crohn's disease, stable medication, low stool calprotectin, and no exercise contraindication. - Sample size: 36 - Age: Mean 36.9 years (SD 11.2); eligible age range 16-65 years. - Sex: 17 male, 19 female. - Fitness level: Not currently participating in more than 90 min/week of purposeful exercise; baseline peak oxygen uptake about 27-29 mL/kg/min across groups. - Health status: Crohn's disease, mostly quiescent (89%) with some mildly active disease (11%). ## Methodology - Multi-centre, three-arm, parallel-group, mixed-methods pilot randomized controlled trial. - 12-week supervised training intervention with assessments at baseline, 3 months, and 6 months after randomization. - Recruitment from three hospital trusts in England; exercise delivered in exercise science facilities at the University of East London and University of Winchester. - Randomized and controlled study design. ## Protocol - HIIT. - Modality: Leg cycle ergometer. - Work intervals: 1 min at 90% Wpeak. - Recovery: 1 min at 15% Wpeak. - Sets or repetitions: 10 bouts. - Intensity: Prescribed from Wpeak; achieved mean heart rate 92% of maximum at interval 9 and RPE around hard. - Session duration: 28 min including 5-min warm-up and 3-min cool-down. - Frequency: 3 sessions/week. - Program length: 12 weeks. - Progression: Wpeak retested in final sessions of weeks 4 and 8 to adjust power output. - MICT and usual care control. - Modality: MICT: leg cycle ergometer; control: no trial exercise. - Work intervals: MICT conditioning phase was continuous 30 min at 35% Wpeak. - Recovery: Not interval-based; warm-up and cool-down at 15% Wpeak. - Sets or repetitions: MICT: one continuous conditioning block. - Intensity: MICT at 35% Wpeak; achieved mean heart rate 68% of maximum and moderate RPE. - Session duration: 38 min for MICT. - Frequency: 3 sessions/week for MICT. - Program length: 12 weeks supervised training for MICT; usual care control followed for 6 months. - Progression: MICT Wpeak retested in final sessions of weeks 4 and 8 to adjust power output. ## Outcomes ### Exercise attendance Status: mixed HIIT attendance was 62% of offered sessions and MICT attendance was 75%; all attended sessions were completed as planned. HIIT 288/465 sessions; MICT 320/429 sessions; 8/13 HIIT and 8/12 MICT completed at least 24 of 36 sessions. ### Exercise enjoyment and acceptability Status: improved Both exercise programs were reported as enjoyable and interview feedback was generally positive. PACES mean 99.4 (SD 12.9) for HIIT and 101.3 (SD 17.4) for MICT out of 126. ### Peak oxygen uptake Status: improved Mean change in peak oxygen uptake relative to control was greater after HIIT than MICT. Relative to control: HIIT +2.4 mL/kg/min vs MICT +0.7 mL/kg/min; no formal hypothesis testing. ### Peak power output Status: improved Peak power output increased more in HIIT than MICT or control. Mean change: HIIT +24 W (SD 17), MICT +12 W (SD 16), control +4 W (SD 14). ### Safety Status: mixed Three non-serious exercise-related adverse events occurred, and two exercise participants experienced disease relapse during follow-up. All exercise-related adverse events were in the HIIT group; relapses occurred in one HIIT participant and one MICT participant. ## Practical Insights - A 10 x 1-min cycling HIIT protocol can be feasible in screened, supervised adults with quiescent or mildly active Crohn's disease. - Three weekly sessions may be a meaningful adherence barrier for some users, even when supervised. - Flexible scheduling and weekend availability may improve clinical exercise adherence. - Cycling may be more acceptable than running for some Crohn's disease users because running can trigger bowel urgency. - Hydration and meal timing guidance should accompany hard intervals in sensitive populations. ## Limitations - Pilot trial with small sample size and no formal efficacy hypothesis testing. - Upper recruitment target of 45 was not achieved. - Self-reported physical activity may be inaccurate. - No endoscopy to directly visualize gastrointestinal effects of exercise. - Participants could not be blinded to allocation, creating risk of bias in patient-reported outcomes. - Generalizability to other sites and unsupervised settings remains uncertain. ## Safety And Adherence - Three non-serious exercise-related adverse events occurred in HIIT: dehydration-related headache/dizziness on two occasions in one participant and vomiting after one session in another participant. - One unrelated non-serious chest infection occurred after randomization. - One HIIT participant and one MICT participant experienced disease relapse between baseline and 3 months. - Authors judged the HIIT relapse likely due to progressive disease while off treatment and the MICT relapse possibly related to medication switch. ## Original Sources - [PubMed](https://pubmed.ncbi.nlm.nih.gov/30696423/) (pubmed) - [DOI](https://doi.org/10.1186/s12876-019-0936-x) (doi) - [PMC full text](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6352351/) (full text) ## Agent Guidance Preserve the paper-level scope of this note. Do not generalize beyond the population, protocol, measured outcomes, and limitations above.