This study will investigate the effect of a 12-weeks cardiac rehabilitation training (HIIT, MICT) program on VO2peak and cardiac fibrosis in patients, and evaluate the effects of HIIT on endothelial function, microvascular obstruction, body fat, inflammation, arrhythmia and psychology .

Eligible and consenting patients are randomized (block randomization) in a 1:1:1 ratio. According to the number of 180 samples calculated by the sample size, the random number table containing 1-180 ( including shedding cases ) was obtained by the computer. Case number will be assigned to participants in each group according to the order of grouping, and each case number corresponded to Group1(HIIT), 2(MICT) or 3(Control) according to the random number.

The HIIT sessions include brief, intermittent bouts of high-intensity exercise interspersed with periods of low-intensity exercise (active recovery). HIIT include 20 intervals of high-intensity (30-60s at rating of perceived exertion (RPE; Borg scale of 6-20) of 15 to 17) and low-intensity (1min at RPE <10 or totally rest). The whole exercise cycle takes around 40-50 minutes (Figure 2). In MICT Group, patients perform 40-50 minutes at a RPE of 12 to 14(a total of 4 groups, each group 5-8 min, interspersed with 2-minute rest)(Figure 3). HIIT and MICT are performed only during supervised sessions with non-consecutive 3 days/week. And all patients are supervised by professional CR team. After assessing by therapists and doctors, participants also can perform three days of home-based exercises guided by wearing a sports bracelet.

The CR program includes 36 sessions supervised exercises, pharmacological counseling, patient education, catering management, smoking cessation counseling, stress management, and psychological counseling. A standard 36 sessions of CR usually lasts 12 weeks (three sessions per week).

Inclusion Criteria:

1. Aged 18 -75 years
2. Acute myocardial infarction (AMI) patients between 6 weeks and 3 months and had been underwent revascularization, and New York Heart Association functional classification (NYHA) Class I-III; (AMI confirmed by the World Health Organization definition (presence of symptoms of ischemia and changes in electrocardiogram) or the Third Universal Definition of Myocardial Infarction (elevation of a cardiac biomarker along with presence of either symptoms of myocardial infarction or changes in electrocardiogram))
3. Willing and able to attend the complete cardiac rehabilitation(CR)program on their own，assigned the Informed consent form.
4. Complete the cardiopulmonary exercise testing (CPET) at enrollment or has the CPET report within 1 month.

Exclusion Criteria:

1. High-intensity exercise frequently
2. Currently participating in any other clinical trials
3. Have any other diseases which limit their life to less than a year (e.g. severe valvular disease, recurrent ventricular arrhythmias, NYHA Class IV heart failure, severe aortic incompetence, severe atrial fibrillation, cancers, and end-stage renal or liver disease)
4. Dementia ; disability or sports contraindication
5. Severe acute liver failure
6. Severe acute renal failure
7. Unstable vital signs
8. Site investigators consider that the patient will be unable to complete the study and/or attend for follow-up.

All data (including data dictionaries) from individuals consent to the present project, after de-identification, will be shared that include all been discussed in this article. Study protocol, statistical analysis plan, and analytic code are available for sharing. We anticipate data sharing will be ready 6 months after the publication of the primary end point of this project, and ending 36 months following article publication. Our data may be shared with investigators who provide a methodologically sound proposal with approval of an independent review committee. Proposals should be directed to gengqsh@163.net. To gain access, data requestors will need to sign a data access agreement with our institution. Data are available for 5 years at the data management center.

5 years