Age

Any age

Sex

ALL

Healthy volunteers

Not accepted

Diagnosed with COPD satisfying GOLD criteria (Agusti, 2022) ;
Being Chinese;
Able to understand, speak, and hear;
Clinically stable for at least three months prior to enrollment (Soler-Cataluna et al., 2018) ;
The classification of GOLD grades for patients is mild, moderate, and severe, which means: FEV1/FVC\<70%, FEV1\>30%pre (Agusti, 2022) ;
Participants who were mindful about the IT technology and known how to use a smartphone.

Impaired hand function causing inability to use the application;
Have disorders in pleural effusion, pulmonary malignancy, heart diseases, stroke with sequels;
Patients who have oral or nasal diseases cannot complete the exercise.

Development and Feasibility Testing of Digital Theory-based Pursed Lip Breathing in Stable Patients With COPD