Comparison of high-intensity interval training versus moderate-intensity continuous training in pulmonary rehabilitation for interstitial lung disease: a randomised controlled pilot feasibility trial
Question
Is HIIT feasible and more effective than moderate-intensity continuous training during pulmonary rehabilitation for people with interstitial lung disease?
Summary
In a pilot randomized trial of pulmonary rehabilitation for interstitial lung disease, HIIT was feasible and had no reported adverse events, but it required closer supervision to maintain target heart rate while avoiding oxygen desaturation. Improvements in walking distance appeared earlier with HIIT but were smaller and less durable than with moderate continuous training. The authors concluded that moderate continuous training is more appropriate for general pulmonary rehabilitation, while HIIT may have a narrower role when faster short-term gains are needed.
Methodology
- Symptomatic ambulatory adults with interstitial lung disease referred from a tertiary ILD centre.
- 58 participants.
- Circuit-based pulmonary rehabilitation using treadmill walking, brisk cone walking, cycle ergometer, trampette, step-ups, and strength exercises.
- Work intervals: Dynamic high-intensity intervals; week 1 averaged about 2.5 minutes at 80% HRmax for each aerobic exercise.
- Recovery: Low-intensity or rest phases between high-intensity efforts.
- Intensity: Target 80% HRmax during high-intensity portions.
- 1 hour exercise plus 1 hour education.
- Twice weekly for 8 weeks, then home/community exercise 3 times per week plus daily walking.
- 8-week outpatient PR plus 6-month community program.
- Single-blind randomized controlled pilot feasibility trial
- Feasibility, Six-minute walk distance, Respiratory and limb strength, and Health status and mood were tracked.
Outcomes
Feasibility and supervision
HIIT was feasible and well tolerated but required closer supervision to hit HR targets while avoiding oxygen desaturation.
Safety
No adverse events were reported during or after pulmonary rehabilitation.
Attrition
Attrition was numerically higher in HIIT than MICT, though not clearly attributed to intervention type.
HIIT 42% vs MICT 28%.
6-minute walk distance
Both groups improved, but MICT produced a larger and more durable improvement; HIIT peaked earlier and declined faster.
Peak improvement MICT 51.6 m (29.2 to 73.9) vs HIIT 26.3 m (3.5 to 49.1); group-time p=.006.
Secondary outcomes
Secondary outcomes generally improved or followed similar faster/smaller HIIT patterns, without HIIT superiority.
Clinical interpretation
The results favored MICT as the more appropriate general PR option, with HIIT possibly useful only for selected fast-gain contexts.
Insights
- HIIT for ILD requires close oxygen-saturation and symptom monitoring.
- Moderate continuous training may be the safer default in general pulmonary rehab because it was more durable and required less supervision.
- HIIT may be considered only in specific supervised contexts where faster short-term gains are important.
Limitations
- Pilot feasibility trial with small sample.
- Baseline DLCO was lower in the HIIT group.
- Supplemental oxygen was not added during sessions except for patients already using LTOT.
- Few IPF completers and all LTOT participants did not finish PR.
- Not designed or powered as a definitive superiority trial.
Safety
- No adverse events were reported.
- HIIT required closer supervision to avoid oxygen desaturation below 85%.
- This clinical pulmonary population is not suitable for unsupervised generic HIIT without medical guidance.