Feasibility and Tolerance of High-Intensity Interval Training in Adults With Cystic Fibrosis.

The trial was not blinded: everyone knew which training programme they were doing. Rehabilitation lasted only 18 days, and the authors say a longer programme might give different results. 62 people were enrolled against a planned 100, and that target was not based on a formal power calculation, so the study cannot rule out small differences between the two approaches. Most participants were already taking CFTR modulator therapy, which improves fitness on its own and may reduce how much people feel they need intensive rehabilitation. Heart rate targets for the interval sessions were set from an age-based formula rather than a measured maximum heart rate or heart rate reserve. Effectiveness was judged with the six-minute walk test rather than peak oxygen uptake from cardiopulmonary exercise testing, which the paper describes as the standard in cystic fibrosis. The subgroup findings, including the poorer tolerance in people with severe respiratory impairment or not taking modulators, rest on very small numbers. Only six participants were malnourished, so nutritional status could not be analysed. Recruitment was affected by the COVID-19 pandemic.

The authors list no disclosures. The paper states no funding source and gives no information about who paid for or had a role in the study.

Do not read this as showing high-intensity interval training is better than conventional rehabilitation. Both groups improved by similar amounts in walking distance, quadriceps strength, lung function and quality of life, and the only differences between groups were slightly better session completion plus lower enjoyment of exercise in the high-intensity group.