Using Enhanced External Counterpulsation to Recover Cardiovascular Function for Patient of Chronic Diseases

Brief Summary

The goal of this clinical trial is to learn whether enhanced external counterpulsation (EECP) therapy can improve cardiopulmonary function and symptoms in adults with long COVID. It will also evaluate the safety and feasibility of two different EECP treatment schedules. The main questions it aims to answer are: * Does EECP therapy improve functional exercise capacity and cardiopulmonary performance in patients with long COVID? * Do different EECP treatment schedules (standard vs. accelerated sessions) lead to different improvements in symptoms, quality of life, and physiological outcomes? * What side effects or medical problems occur during EECP therapy? Researchers will compare two EECP treatment schedules to determine whether a shorter, accelerated program provides similar benefits to the standard schedule. Participants will: * Receive EECP therapy either 1 hour per day (5 days per week for 7 weeks) or 2 hours per day (5 days per week for about 4 weeks), both totaling 35 hours of treatment * Visit the cardiopulmonary rehabilitation clinic regularly for supervised treatment sessions * Complete physical performance tests (such as the Six-Minute Walk Test and cardiopulmonary exercise testing) * Have blood pressure and heart rate measured * Complete questionnaires about symptoms, physical function, sleep quality, and quality of life