The study will investigate the effects of different training types ,including combined inspiratory with expiratory pressure threshold training,inspiratory pressure threshold training on patients with chronic obstructive airway disease and investigate whether expiratory pressure threshold training associated with inspiratory pressure threshold training would be better than inspiratory pressure threshold training alone, with regard to exercise capacity, respiratory muscle strength and endurance.

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.

Inclusion Criteria:

Clinically stable COPD with diagnosis of forced expiratory volume at one second(FEV1)/forced vital capacity(FVC) < 70%

Exclusion Criteria:

Cancer Unstable heart disease Neuromusculoskeletal disorder mental disorder Active smokers