High-intensity interval training and moderate-intensity continuous training in adults with Crohn's disease: a pilot randomised controlled trial
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.
Methodology
- Adults and older adolescents with quiescent or mildly active Crohn's disease, stable medication, low stool calprotectin, and no exercise contraindication.
- 36 participants.
- Leg cycle ergometer.
- Work intervals: 1 min at 90% Wpeak.
- Recovery: 1 min at 15% Wpeak.
- Intensity: Prescribed from Wpeak; achieved mean heart rate 92% of maximum at interval 9 and RPE around hard.
- 28 min including 5-min warm-up and 3-min cool-down.
- 3 sessions/week.
- 12 weeks.
- Multi-centre, three-arm, parallel-group, mixed-methods pilot randomized controlled trial.
- Exercise attendance, Exercise enjoyment, Peak oxygen uptake, and Disease activity were tracked.
Outcomes
Exercise attendance
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
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
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
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
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.
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
- 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.