The goal of this clinical trial is to investigate whether an astaxanthin-based dietary supplement combined with a pulmonary rehabilitation training program could improve exercise capacity in patients with COPD. The main questions it aims to answer are:
• whether an astaxanthin-based dietary supplement combined with a pulmonary rehabilitation training program could improve 6MWD in patients with COPD.
The drug administration group will receive:
* Two capsules of astaxanthin formula supplement daily for 8 weeks.
* Pulmonary rehabilitation training: a total of 8 weeks, 2-3 times a week.
The control group will receive a total of 8-week pulmonary rehabilitation training, 2-3 times a week.
The investigators will compare the drug administration group and the control group to see if the difference between the 2 groups reaches a minimal clinically important difference.