Inclusion Criteria:  Confirmed diagnosis of COPD at the outpatient thoracic medicine clinic Need HFCWO as judged by the doctor  Exclusion Criteria:  Acute COPD exacerbation within the previous 4 weeks, Contraindication for WBVT (e.g., artificial joint replacement, a history of deep vein thrombosis, or known aortic aneurysm) Inability to perform squatting exercises Acute disc disease Inability to complete the 6MWT