Validation of Walking Trails for the Urban Training™ of Chronic Obstructive Pulmonary Disease Patients. oleh Ane Arbillaga-Etxarri, Jaume Torrent-Pallicer, Elena Gimeno-Santos, Anael Barberan-Garcia, Anna Delgado, Eva Balcells, Diego A Rodríguez, Jordi Vilaró, Pere Vall-Casas, Alfredo Irurtia, Robert Rodriguez-Roisin, Judith Garcia-Aymerich, Urban Training™ Study Group