COPD patients have a reduced exercise tolerance due to a ventilatory limitation.

Several studies have shown altered skeletal muscle function. The investigator will study the physiological response to knee-extensor exercise in COPD patients.

Reduced exercise tolerance is one of the hallmarks of COPD. The principal causes for exercise intolerance are ventilatory limitation leading to deconditioning and inactivity. However the weak correlation between exercise capacity and FEV1 implies that other factors than reduced pulmonary function contribute to this impairment as well. Several studies have found changes in skeletal muscle, with fibre shift, increased oxidative stress, increased inflammatory cytokines and impaired mitochondrial function, suggesting a lower limb dysfunction.

Numerous exercise studies in COPD patients have shown physiological and physiological benefits of training and endurance training is now regarded as an important part in pulmonary rehabilitation.

In this study we investigate training effects in patients with moderate to severe COPD with special focus on skeletal muscle.

COPD patients will perform high intensity aerobic interval knee-extensor exercise training 3 days/week for six weeks . At baseline and follow-up, muscle oxygen consumption and mitochondrial respiration will be measured.

Inclusion Criteria:

• COPD diagnosis with FEV1<70% exp, FEV1%FVC <70 %
• Age> 50 years

Exclusion Criteria:

• Heart failure
• Symptomatic coronary artery disease
• Cancer
• Alcohol and drug abuse
• Severe mental illness
• Lower respiratory illness
• Participation in exercise- or lung rehabilitation program last 3 months
• pregnancy
• oral steroid use