To achieve the purpose of this study, forty-eight male Sprague-Dawley rats were assigned to control and three endurance exercise group. 36 rats were forced to exercise according to exercise intensity for 8 weeks and 12 rats were untrained for control group. Cardiac cytosol was extracted from cardiac tissue and cardiac mitochondria was purified from the cytosol. Purified mitochondria were separated into four fraction: inner membrane, outer membrane inter membrane space and matrix. The changes of cytosolic and mitochondrial LDH isozymes activity were measure. Relative activity $(\%)$ of cytosol for low and control group showed the following order of prevalence $AB_3>A_2B_2>B_4>A_3B>A_4$ for moderate and high group : $AB_3>B_4>A_2B_2>A_3B>A_4$. Outer membrane for low group showed $AB_3>B_4>A_2B_2$, for moderate group:$ B_4>AB_3>A_2B_2$, for high and control group: $B_4>A_3B$. Inter membrane space for low, moderate and high group showed $B_4>AB_3>A_2B_2>A_3B>A_4$, for control group: $B_4>A_3B>AB_3>A_2B_2>A_4$. Inner membrane for all group showed $B_4>AB_3>A_2B_2>A_3B>A_4$. Matrix for control, low, moderate and high group showed $B_4>AB_3>A_2B_2>A_3B>A_4$. These results suggest that long term exercise intensity effect on cardiac tissue cytosolic and mitochondrial activity and $A_4,;A_3B,;A_2B_2,;AB_3;and;B_4$ isozymes were found entirely in mitochondrial fraction.