 The investigators objective is to investigate the impact of COPD on key signaling pathways involved in the muscle atrophy. Moderate to severe COPD patients FEV1 under 60 of predicted and healthy controls will be recruited. All of the investigators patients will undergo a thorough baseline assessment in pulmonary capacity, muscle force and body composition. Blood sampling and biopsy of the quadriceps will be done. Key proteins of signaling intramuscular pathways involved in protein synthesis and degradation will be measured in the quadriceps. 