The aim is to study effectiveness of inspiratory muscle training as a part of exercise training in patients with Chronic Obstructive Pulmonary Disease (COPD) and if it adds to general exercise training program in regard to respiratory muscle strength, dyspnea, exercise performance and quality of life.

Inclusion Criteria:

• Exsmokers
• Low PImax compared to reference values [lower limits of normal: 80 cmH2O for patients less than or equal 54 years old; 71 cmH2O for patients' age between 55-64 years; and 65 cmH2O for patients 65 years old ].
• Stable patients without history of exacerbation or hospitalization four weeks before starting the study.

Exclusion Criteria:

• Lack of motivation and compliance.
• Patients with significant reversibility following bronchodilation defined as an increase in FEV1 of more than 12% and 200 ml from the pre-bronchodilator value
• Unstable cardiac disease [severe heart failure, dangerous dysrhythmias, recent myocardial infarction or unstable angina (within 4 weeks)].
• Uncontrolled hypertension
• Recent pneumothorax (within 6 weeks)
• Recent abdominal or thoracic surgery (within 6 weeks)
• Known progressive neuromuscular disorders
• Recent gastrointestinal bleeding (within 4 weeks)
• Current smokers
• Active cancer
• Patients with advanced liver diseases, or renal impairment.
• Known connective tissue diseases
• Significant endocrinal abnormalities