Subjects

Patients were included in the study if they fulfilled the inclusion criteria of a diagnosis of COPD according to the Global initiative for Chronic Obstructive Lung Disease (GOLD) recommendations,26 having completed a PRP including exercise training and education component as recommended,27 and written consent signed by the patient prior to the beginning of the program. Patients from Nantes were included in the cohort RehaEffort from the Institut de Recherche en Santé Respiratoire des Pays de la Loire and patients from North Brittany were from the Centre Hospitalier des Pays de Morlaix. Exclusion criteria were the presence of a lower-limb lesion hampering the measurement of quadriceps strength and the presence of joint limitations. The patients were recruited in three different centers in two cities of France: the University Hopsital of Nantes and the Tourmaline Medical Centre in Nantes and the Centre Hospitalier des Pays de Morlaix in Morlaix. In Nantes, the study was conducted by the RehaEffort cohort group from the Institut de Recherche en Santé Respiratoire des Pays de la Loire, for which approval was obtained from the ethical board (Comité de Protection des Personnes [CPP] – 2009/17) and the Comité Consultatif sur le Traitement de l’Information en Matière de Recherche dans le Domaine de la Santé [CCTIRS] (07.207 bus). Patients from the Centre Hospitalier des Pays de Morlaix signed a written informed consent in accordance with the Declaration of Helsinki and the current guidelines for Good Clinical Practice after approval by the institutional medical ethics committees (CPP Ouest 6 – CPP803, 2013-A01180-45).