The purpose of this study is to prove the difference of muscular damage between middle-aged female members of marathon clubs who participate in the life time sports and normal middle-aged women by observing their Cardiorespiratory function and the activity of LDH(Lactate Dehydrogenase) and CPK(Creatine Phosphokinase) in blood. The subjects of study are female members of marathon clubs (n=6) and non-marathon women(n=6) in their 40's. As Maximal Graded Exercise using Bruce Protocol, it is forced to completed when the subjects become state of all-out. Cardiorespiratory function is verified and the activity of LDH and CPK activity is analyzed when the th blood is drawn at rest, after each of 3 minutes recovery and 30 minutes recovery. Data is dealt with independently by the means of t-! test and repeated ANOVA, and post testing of Duncan is done for the significant difference. It is as follows. Oxygen intake and exercise sustaining power of marathon group appear higher than those of non-marathon group in Cardiorespiratory function, and there is a statistical significant difference(p<0.5). The LDH change of Marathon group is higher that of non-marathon group after Maximal Graded Exercise test, but there is no statical significant difference. At the timing of testing at rest, after the 3 minutes and 30 minutes recovery, obviously it shows a higher statical significant difference. The CPK change of marathon group is higher than that of non-marathon group at groups' comparison, and there is a statical significant difference(p<0.5). Also, on the timing of testing after 3 minutes and 30 minutes recovery by completing exercise, a statical significant difference is seen highly in CPK change (p<0.5). As a consequence of the fact above, marathon influences the ability of the oxygen consuming exercise. The marathon group has possibility of damaging their muscular under considering the change of CPK and LDH, which marathon group shows significant differences rather than non-marathon group. It is estimated that excessive and long time exercise could be harmful.