Spirometric lung volumes, respiratory muscle strength, arterial blood gases, and quality of life will be recorded in both groups pre-to-post PR. Perceived dyspnea (by VAS scale), sputum volume and characteristics (on a semi-quantitative 3-point scale) and peak expiratory air flows (PEF and PCEF) will be registered on a daily basis over the study period. Primary outcome is the change in perceived dyspnea; in order to ensure 80% power to detect a 5 point (SD 5) group difference change in the primary outcome at the end of the study period as significant at the 0.05 level, at least 42 patients per group are needed. The minimum target sample size will be then fixed at 50 patients per group.