Inclusion Criteria:  People have below conditions could be included:  age is 18-60 years. have normal ECG . agree to participate in the study.  Exclusion Criteria:  People have below conditions will be excluded:  have known Congenital heart disease and rheumatic heart disease. have known Hypertension and cerebrovascular disease. have known Myocarditis and other heart diseases. have known Coronary artery disease and severe arrhythmia. have known Diabetes with high or low blood glucose. have a cold within two weeks before the study.  have other diseases considered unsuitable for participants in this study.  -