Patients with very severe COPD (GOLD IV);

Patients that had a COPD exacerbations within the preceding 2 weeks of the baseline assessments;

Significant hypoxemia at rest or during exercise (SpO2 \<85%);

Already following a rehabilitation program;

Have physical limitations that compromises participation to a Tai chi and a conventional exercise program

Chen-style Tai Chi in Pulmonary Rehabilitation for Chronic Obstructive Pulmonary Disease