[Skeletal muscle dysfunction in COPD]

Abstract

Muscle function is frequently affected in patients with chronic obstructive pulmonary disease (COPD), influencing the symptoms and prognosis of this disease. The distribution and severity of this dysfunction are heterogeneous and therefore the main causes seem, in part, to be specific to the muscular group examined, which is the case of the overactivity and unfavorable geometry characteristic of respiratory muscles, compared with the relative inactivity of the muscles of the limbs. There are also factors that are common to all the muscles in the body. Notable among these factors are systemic inflammation, nutritional alterations, the use of certain drugs, hypoxia and the presence of comorbidity and/or advanced age. However, while the respiratory muscles show a phenotype adapted to their unfavorable situation and manage to partially compensate for this situation, the muscles of the limbs show involutive changes, which contribute to dysfunction. Therefore, although functional loss can develop in distinct muscular territories, the causes - and consequently the therapeutic approaches - differ, including nutritional support, muscle training and/or rest, depending on the muscle.