The purpose of this clinical trial is to explore whether Phase I cardiac rehabilitation can treat elderly patients with coronary heart disease complicated by sarcopenia. It will also investigate the mechanism of Phase I cardiac rehabilitation. The main questions it aims to answer are:

• Can Phase I cardiac rehabilitation enhance muscle strength ?
• Can Phase I cardiac rehabilitation reduce in vivo inflammatory indicators? Researchers will compare the experimental group (Phase I cardiac rehabilitation + drug therapy + general treatment) with the control group (drug therapy + general treatment) to see if Phase I cardiac rehabilitation can treat elderly patients with coronary heart disease complicated by sarcopenia and reduce inflammatory indicators.

Participants will:

• Receive Phase I cardiac rehabilitation training（mainly includes low-intensity resistance training, breathing training and bedside cycling） or conventional drug therapy for 3 consecutive months.
• Undergo examinations 10 days after training, 1 month after discharge, and 3 months after discharge respectively.
• Record changes in their muscle strength and blood inflammatory indicators.

The main purpose of this study is to explore the clinical efficacy of Phase I cardiac rehabilitation in the treatment of elderly patients with coronary heart disease complicated by sarcopenia and its potential clinical mechanisms.

The determination of this sample size is based on research hypotheses and estimates of the expected efficacy level, calculated in accordance with statistical principles. The PASS software was used for sample size estimation, with a significance level (alpha) of 0.050. Using the two independent samples t-test, 15 cases in the experimental group and 15 cases in the control group were needed to achieve a test power of >90%. To enhance the statistical power of the results, it was decided to include 50 cases in the experimental group and 50 cases in the control group, totaling 100 patients.

Research participants with high compliance were screened. Before the start of the clinical trial, researchers provided sufficient education to the participants, including the trial process, potential benefits and risks, as well as the rights and obligations of the participants. Only after the participants fully understood the trial and signed the informed consent form could they be enrolled.

SPSS generated a random number table. According to the table, odd numbers were assigned to the intervention group and even numbers to the control group, and simple randomization was used for group allocation. Statistical result analysis will be conducted at the 0.05 significance level, using SPSS statistical software.

Risk monitoring will be carried out during the trial: closely observe abnormal situations during the trial to prevent risks; promptly identify various types of risks; and on the basis of risk identification, conduct risk assessment. If risks occur, corresponding risk handling strategies will be formulated according to different risk levels. In the event of a serious adverse event, researchers will report it to the regulatory authorities and the ethics committee within 24 hours and fill out a serious adverse event report form.

Inclusion Criteria:

• Age ≥ 60 years;
• Coronary heart disease confirmed by coronary CTA or coronary angiography, with stable condition within the past 8 hours, including: ① no new or recurrent chest pain; ② no further elevation of troponin level; ③ no new signs of decompensated heart failure (dyspnea at rest accompanied by moist rales); ④ no new malignant arrhythmias or dynamic changes in electrocardiogram. Basic vital signs are normal, including: ① resting heart rate of 50-100 beats per minute; ② resting blood pressure of 90-150/60-100 mmHg (1 mmHg = 0.133 kPa); ③ oxygen saturation > 95%.
• Meeting the diagnostic criteria for sarcopenia (2024 Edition of Chinese Guidelines for the Diagnosis and Treatment of Sarcopenia);
• Having good compliance to ensure the completion of this study;
• Being able to understand the purpose of the trial, voluntarily participating in the study and signing the informed consent form.

Exclusion Criteria:

• Severe arrhythmia, decompensated heart failure, severe respiratory failure, untreated severe aortic stenosis, acute aortic dissection, resting hypertension with systolic and/or diastolic blood pressure > 200/110 mmHg;
• Mental disorders with limited cooperation ability; severe cognitive or behavioral disorders; end-stage diseases; acute diseases (e.g., acute infections, injuries) that restrict physical activity;
• Poor compliance and inability to cooperate with the completion of this study.