Physical inactivity: common pathway to peripheral muscle weakness in chronic respiratory diseases?

L ower limb muscle atrophy and weakness are common in patients with chronic obstructive pulmonary disease (COPD) and make an important contribution to limiting their exercise tolerance [1]. Muscle disuse, hypoxaemia, malnutrition, oxidative stress and systemic inflammation have all been portrayed as possible causes of muscle dysfunction in COPD [2]. As far as systemic inflammation is concerned, the available literature supports cytokine-mediated effects on peripheral muscle atrophy, dysfunction and regeneration [3].