Patients with severe Chronic Obstructive Pulmonary Disease (COPD) and low oxygen levels in the blood are at risk of developing pulmonary hypertension and strain on the right side of the heart, both of which are known to increase symptoms and worsen prognosis It is not fully established whether interval exercise training in patients with severe COPD and concomitant low oxygen levels is beneficial.

This study aims to evaluate the effects of aerobic interval exercise training in patients with severe COPD and low oxygen levels in the blood, with a particular emphasis on such effects on the cardiovascular system and pulmonary circulation.

Inclusion Criteria:

• Chronic Obstructive Pulmonary Disease (COPD)
• Forced Expiratory Volume 1 second (FEV1) <60% of predicted
• FEV1%FVC <70 % of predicted (FVC = Forced Vital Capacity)
• Qualify for Long term oxygen therapy (LTOT), or presence of significant desaturation on exercise.

Exclusion Criteria:

• Unstable ischaemic heart disease or valvular heart disease.
• Active malignant disease.
• Substance abuse.
• Physical or mental disability that prevents participation in the exercise programme or testing.
• Pregnancy.
• Exacerbation of COPD or respiratory tract infection last 6 weeks before.
• Completed pulmonary rehabilitation programme or other organised exercise programme last 3 month
• Use of high doses of systemic steroids.