Although high-intensity training (HIIT) is widely used in the rehabilitation of patients with chronic obstructive pulmonary disease (COPD), the optimal duration of intervals in terms of patient tolerability and fidelity is unknown.Thus, we will examine the fidelity and tolerability of the two most commonly used HIIT protocols, the classical so-called 4x4min vs. 10x1min in patients with moderate to severe COPD.

12 patients with severe to moderate COPD will be included in the study, where two different HIIT interventions will be compared with regards to fidelity and tolerability. Baseline measurements will be performed to assess fitness and cardiopulmonary health status for the included patients. The baseline measurements include a medical health interview and examination (blood pressure, heart rate, ECG), a maximal oxygen consumption (VO2max) test, lung function testing (dynamic spirometry, whole body plethysmography, diffusing capacity), and an assessment of body composition. The following two visits consist of two different HIIT protocols.

Each training session is evaluated by Borg Scale (5) and the Likert Scale (6), as well as time spent in with a heart rate above 85% of maximum. Each HIIT session is separated by at least a 3-day wash-out period.

Inclusion Criteria:

• Men and women
• 18-80 years
• Moderate to severe COPD(GOLD stage II to III)

Exclusion Criteria:

• Known ischaemic heart disease
• Known heart failure
• Previous or current coronavirus disease 2019 (COVID-19)
• Dementia or other severe neurological disease
• Known vascular
• Symptoms of disease within 2 weeks prior to the study
• Pregnancy