Due to persistent challenges in participant recruitment, the study has been terminated and the protocol has been formally withdrawn.

This study aims to investigate the effects of elliptical exercise on the six-minute walk test and quality of life in patients with chronic obstructive pulmonary disease (COPD) to identify the most efficient exercise training method.

Background： Chronic respiratory diseases, including COPD, are leading causes of chronic illness and mortality worldwide. However, limitations in ventilation and muscle function restrict COPD patients from engaging in higher-power exercise therapies. Compared to concentric exercise, eccentric exercise can effectively improve health-related fitness and quality of life at lower cardiopulmonary and metabolic loads. Pulmonary rehabilitation programs have been shown to effectively improve symptoms of chronic respiratory diseases, increase exercise capacity, enhance quality of life, delay disease progression, prevent and treat acute exacerbations, and reduce mortality. Therefore, it is hoped that a "safe and effective" eccentric exercise strategy can be designed for COPD patients to comprehensively improve their cardiopulmonary/muscle fitness and quality of life, thereby improving the course of their disease.

Study Design： This is a one-year, single-center, prospective randomized controlled trial. Methods： This study plans to enroll 60 participants who will be randomly assigned to control and experimental groups. The intervention will take place in the pulmonary rehabilitation room on the sixth floor of Fu Jen Hospital. Each group will undergo a functional fitness test and complete a quality of life questionnaire before and after 24 sessions (over 12 weeks) of exercise training.

Effect： It is anticipated that after 24 sessions of elliptical exercise training, there will be an improvement in the functional fitness and in quality of life related to physical activity function.

Key words： Pulmonary rehabilitation; eccentric exercise; chronic obstructive pulmonary disease; cardiopulmonary fitness; functional fitness

Inclusion Criteria:

• Having undergone pulmonary rehabilitation for more than 3 months
• Sign the written informed consent form
• FEV1/FVC < 0.70
• Approval for exercise training granted by a specialist physician's assessment
• Specialist physician's approval for exercise training

Exclusion Criteria:

• Existing of tracheostomy
• Those who use oxygen therapy or ventilator at home
• Severe heart failure (NYHA III-IV)
• Neuromuscular disease
• Acute exacerbation within the past three months
• Those who are unable to cooperate with the cardiopulmonary exercise test