The goal of observational study is to evaluation of skeletal muscle function in patients with chronic obstructive pulmonary disease before and after lung rehabilitation training using ultrasonic elastography in Chronic Obstructive Pulmonary Disease. The main question it aims to answer are:Evaluation of skeletal muscle function in patients with chronic obstructive pulmonary disease before and after lung rehabilitation training using ultrasonic elastography.

Participants will undergo pulmonary rehabilitation.

Inclusion Criteria:

• The age is between 40-80 years old
• Patients with chronic obstructive pulmonary disease who meet the diagnostic criteria of GOLD guideline(2019)
• There was no acute exacerbation in the past 12 weeks

Exclusion Criteria:

• Hypoxemia (oxygen partial pressure is less than 60mmHg or oxygen saturation is less than 88% at rest), or patients who need continuous oxygen inhalation, or patients with any contraindication to exercise test (refer to the American Thoracic Association/American Association of Thoracic Physicians exercise test guidelines)
• Oral glucocorticoids
• Receive long-term oxygen therapy prescription
• Have participated in supervised exercise programs in the past 12 months
• History of other lung diseases, including pneumoconiosis, bronchiectasis, tuberculosis, primary pulmonary hypertension, pulmonary embolism, interstitial lung disease
• Diseases that restrict the active exercise ability of participants or involve skeletal, neuromuscular, cardiovascular or metabolic disorders of muscle activity, such as tumors, diabetes, muscle weakness, etc

Chronic obstructive pulmonary disease