We will study 60 patients diagnosed of chronic obstructive pulmonary disease.The monitoring will be done for 8 weeks. Pressure-threshold respiratory trainers were calibrated to provide different loads according to the patients against inspiration (IMST) or expiration (EMST). Those chronic obstructive pulmonary disease clinically stable patients stratified from mild to very severe GOLD stages, were blinded to randomly divided into 3 different groups: a)control group:without any training;b) inspiratory and expiratory pressure threshold training group: trained with the pressure threshold trainer twice time daily with 15minutes' duration;c)inspiratory pressure threshold training group:trained with the pressure threshold trainer twice time daily with 15 minutes' duration,different from the b group,the expiratory pressure threshold is calibrated at 0.
