Chronic Obstructive Pulmonary Disease (COPD) ，the fourth leading cause of death in the world, represents an important public health challenge. It is also a major cause of chronic morbidity, mortality and disability throughout the world, leading to a heavy social and economic burden. For a long time, treatment of COPD mainly focus on drug therapy. Recently, pulmonary rehabilitation is recognized as a core component of the management of individuals with chronic respiratory disease, which has been clearly demonstrated to reduce dyspnea, increase exercise capacity, and improve quality of life.

Exercise training, widely regarded as the cornerstone of pulmonary rehabilitation , is one of the best available means of improving muscle function in COPD.The most commonly form is cycle training. Inspiratory Muscle Training (IMT) as an adjunct to exercise training has an additional benefit on inspiratory muscle strength, endurance and exercise capacity in patient with COPD.

There is insufficient evidence demonstrate greater benefits from combined inspiratory muscle training and cycle training. This study will evaluate the effects of combined inspiratory muscle training and cycle training in patients with COPD.

The patients with COPD will participate in a rehabilitation program for 8 weeks. Participants in the proposed study will be randomly programmed into one of three intervention groups:

1. Cycle training program alone (performing on calibrated stationary cycle ergometer).
2. Combined cycle training and inspiratory muscle training(performing on calibrated stationary cycle ergometer and threshold loading device).
3. Neither cycle training nor inspiratory muscle training.

Inclusion Criteria:

• Patients between 40 and 75 years of age were eligible if they met the following criteria:

  • moderate to severe airflow obstruction (30≤ Forced Expiratory Volume At One Second(FEV1) <80% predicted and Forced Expiratory Volume At One Second/Forced Vital Capacity(FEV1/FVC)<70%)
  • Complaints of dyspnea on exertion
  • Clinically stable condition
  • No participation in a pulmonary rehabilitation program in the last year.

Exclusion Criteria:

• Patients were excluded if they had evidence of asthma and/or had experienced a major exacerbation in the 2 months before enrollment
• Required home oxygen therapy or experienced oxyhemoglobin desaturation below 85% with exercise
• And/or had other health problems that would interfere with exercise.