# Comparison of high-intensity interval training versus moderate-intensity continuous training in pulmonary rehabilitation for interstitial lung disease: a randomised controlled pilot feasibility trial PMID: 37607782 Journal: BMJ Open Published: 2023-08-22 Authors: Nikoletou D, Chis Ster I, Lech CY, MacNaughton IS, Chua F, Aul R, Jones PW ## 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. ## Population - Symptomatic ambulatory adults with interstitial lung disease referred from a tertiary ILD centre. - Sample size: 58 - Age: Approximately 70 years mean age - Sex: HIIT 18 male/15 female; MICT 14 male/11 female - Fitness level: Pulmonary rehabilitation population with exertional dyspnoea - Health status: Interstitial lung disease including IPF, CTD-ILD, NSIP, UIP, and chronic hypersensitivity pneumonitis; mMRC dyspnoea 1-3 ## Methodology - Single-blind randomized controlled pilot feasibility trial - 8-week pulmonary rehabilitation plus 6-month community program - Hospital gym pulmonary rehabilitation plus community/home follow-up - Randomized and controlled study design. ## Protocol - HIIT pulmonary rehabilitation. - Modality: 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. - Sets or repetitions: At least 30 minutes aerobic exercise in a 1-hour exercise session plus strength work. - Intensity: Target 80% HRmax during high-intensity portions. - Session duration: 1 hour exercise plus 1 hour education. - Frequency: Twice weekly for 8 weeks, then home/community exercise 3 times per week plus daily walking. - Program length: 8-week outpatient PR plus 6-month community program. - Progression: Weekly increase in high-intensity time by reducing low-intensity phase and/or increasing time at target HR. - Moderate-intensity continuous pulmonary rehabilitation. - Modality: Same circuit-based pulmonary rehabilitation modalities. - Work intervals: Continuous moderate aerobic exercise. - Recovery: Not interval-based. - Sets or repetitions: At least 30 minutes aerobic exercise in a 1-hour exercise session plus strength work. - Intensity: Target 60% HRmax, progressed weekly. - Session duration: 1 hour exercise plus 1 hour education. - Frequency: Twice weekly for 8 weeks, then home/community exercise 3 times per week plus daily walking. - Program length: 8-week outpatient PR plus 6-month community program. - Progression: Moderate continuous training progressed weekly. ## Outcomes ### Feasibility and supervision Status: mixed HIIT was feasible and well tolerated but required closer supervision to hit HR targets while avoiding oxygen desaturation. ### Safety Status: no clear change No adverse events were reported during or after pulmonary rehabilitation. ### Attrition Status: worse/safety concern Attrition was numerically higher in HIIT than MICT, though not clearly attributed to intervention type. HIIT 42% vs MICT 28%. ### 6-minute walk distance Status: mixed 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 Status: mixed Secondary outcomes generally improved or followed similar faster/smaller HIIT patterns, without HIIT superiority. ### Clinical interpretation Status: mixed The results favored MICT as the more appropriate general PR option, with HIIT possibly useful only for selected fast-gain contexts. ## Practical 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 And Adherence - 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. ## Original Sources - [PubMed](https://pubmed.ncbi.nlm.nih.gov/37607782/) (pubmed) - [DOI](https://doi.org/10.1136/bmjopen-2022-066609) (doi) - [PMC full text](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10445364/) (full text) ## Agent Guidance Preserve the paper-level scope of this note. Do not generalize beyond the population, protocol, measured outcomes, and limitations above.