1. University of the Basque Country; Department of Preventive Medicine and Public Health; Barrio Sarriena S.N. Leioa Bizkaia Spain E-48080
2. Biocruces Health Research Institute, Cruces University Hospital; Respiratory Physiotherapy Unit, Rehabilitation Service, Pneumology; Barakaldo Spain
3. Ramon Lull University; Department of Health Sciences; Padilla, 326-332 Barcelona Spain 08025
4. Rehabilidom; Bilbao Spain