A study on 48 middle-aged and elderly joggers through exercise echocardio-graphy and measurements during systolic time intervals (STI) showed that whencompared with a control group of 26 sedentary persons, their stroke volume was44.2% and cardiac output 25.1% greater at rest, 34.3% and 15.8% greater duringequivalent load exercise, and 35.1% and 33.1% grater during equivalent heart rateexercise. In addition, their left ventricular end-diastolic diameter (LVEDd) andleft auricule diameter were also longer and the closing velocity of the mitral valveduring the early diastolic stage was greater, although their ejection fraction, AD%and STI showed no significant difference. This proves that jogging can improvecardiac pumping function by enlarging LVEDd and increasing pre-load of heart.