Interval training in COPD patients with chronic respiratory failure: a feasibility and comparative study

<bold>Background:</bold> To date, there is a lack of studies assessing the impact of High-Intensity Interval Training (HIIT) on Chronic Obstructive Pulmonary Disease (COPD) patients with chronic respiratory failure (CRF). The primary aim of this RCT study was to investigate the safety and acceptability of two different interval training protocols. The focus was to evaluate training volume, symptoms, and the possibility of increasing training volume during the program. <bold>Methods:</bold> This RCT study included three groups undergoing cycle-ergometer exercise training, involving 20 supervised sessions of either constant-load endurance (ET), long interval training (4 minutes/4 minutes phases, Long-HIIT), or short interval training (30 seconds/30 seconds, Short-HIIT). At the beginning, the volume of work /session was similar. <bold>Results:</bold> Patients in the ET and Long-HIIT groups demonstrated greater total work compared to the Short-HIIT group (ET 1168970±255241 J, Long-HIIT 1297717±477250 J, Short-HIIT 1011530±245787, P =0.0489) with a lower level of dyspnea (Borg score: 3,40±1,11 ET, 2,84±1,61 Long-HIIT, 4,05±1,17 Short-HIIT P=0.0174) and fatigue (Borg score: 3,40±1,45 ET, 2,53±1,19 Long-HIIT, 3,54±1,19 Short-HIIT P=0.0466). The increase of intensity (watts) during training was noted in 78% for ET, 84% for long-HIIT, and 46% for short-HIIT groups (P=0.020). No differences were observed among groups in the improvement of the Costant Load Exercise Test and 6 Minute Walking Test, and safety and satisfaction. <bold>Conclusion:</bold> Compared to short-interval training, the long-interval modality allows a greater volume of training volume with lower symptoms in COPD-CRF patients, with similar outcome results.