Abstract: Objectives:The aim of this study is to dissect the function of marker of cardiac progenitor cells (Isl1) in cardiac cell proliferation in adult mammals under different exercise Intensity.Methods:2-month old adult male C57 BL/6 J mice were randomly divided into 3 groups (n=6) :control (C) , aerobic training (A) and excessive exercise (E) .Mice in A and E were underwent 4-week's training program using small animal treadmill with gradually increasing intensity.Heart function was evaluated by small animal echocardiography.Marker of Cardiac Progenitor Cells (Isl1) and Proliferating cell nuclear antigen (PCNA) were observed and analyzed by Real Time PCR.Myocardium was observed hematoxylin-eosin staining.Myocardial enzymes were measured by blood biochemical tests.Results:Exercise resulted in the up-regulation of gene expression both for Marker of Cardiac Progenitor Cells (Isl1) and cell proliferation factor (PCNA) .Different exercise intensity could increase the expression of cardiac progenitor cell marker.The effect of aerobic training was more significant than overload exercise.The results of echocardiography show that aerobic exercise can significantly improve cardiac function and heart coefficient.Conclusions:Exercise can effectively stimulate the mouse heart, increase the expression of endogenous marker of cardiac progenitor cells (Isl1) , promote the expression of Proliferating cell nuclear antigen (PCNA) , and improve heart function.The effect of aerobic training was more significant than excessive exercise for the heart shape and function improvement.Exploring the effects of different exercise intensity on cardiac cell regeneration will help to validate or supplement the influences and mechanisms of cell proliferation and differentiation of adult cardiac progenitor cells, and provide valuable practical basis for sports medicine, sports rehabilitation and preventive medicine.