Exercise therapy is a cornerstone in the management of patients with Chronic Obstructive Pulmonary disease (COPD), and supervised walking exercise three times a week over 12 weeks improves walking ability and quality of life. Despite this, very few patients exercise on a regular basis. The underuse of exercise in COPD patients can partly be explained by discomfort during exercise because it evokes dyspnea, and thereby explain lack of participation in exercise. If the goal is to offer the best medical therapy to these patients, new and effective exercise training methods must be explored and defined since exercise training is an important part of pulmonary rehabilitation.

Intention is to study a new training method called sprint interval training (SIT), which consists of high intensity bouts with very short duration. The idea behind SIT is to avoid the dyspnea associated with traditional endurance training, thus maximizing exercise power without excessive discomfort. The investigators will study training adaptations in patients with COPD and compare the results with age-matched controls.

It is expected that both COPD-patients and healthy elderly will improve exercise cycle time until exhaustion after SIT training, and also that the improvement will be larger in the healthy group due to higher absolute training intensity.

Inclusion Criteria (patients):

• stable CPOD stage 3 and 4 according to GOLD guidelines (www.goldcopd.org)
• post bronchodilator FEV < 50%

Exclusion Criteria:

• having participated in a pulmonary rehabilitation program during the last 3 months.