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.