Background. Exercise intolerance is one of the most devastating consequences of chronic obstructive pulmonary disease (COPD). Abnormalities in peripheral muscle function such as weakness and reduction in oxidative enzyme activities are commonly found in these patients and may contribute to exercise intolerance.To evaluate whether a systemic weightlifting exercise may improve exercise capacity better than endurance training, or a combined training is more effective, the investigators compared three different training regimens, endurance training alone, systemic weightlifting training alone or a combination of both endurance and weightlifting training.