Background: Endurance training can lead to tissue damage and destruction by creating oxidative stress. But, it seems that exhaustive and endurance swimming indicated different results with each other. The purpose of this research was to compare two kinds of endurance swimming training on levels of LDH, CK and MDA in male Wistar rats.

Materials and Methods: 18 male Wistar rats with 12 weeks old, weighting 250 to 300 g, were randomly divided into three groups (6 in each): 1) endurance swimming (EN), 2) exhaustive swimming (EX) and 3) Control (C). Both groups swam for 1 h/d and 5 d/w for 10 weeks. Swimming duration in EX groups was increased progressively by fiveth weeks, by 30 min/week, reaching 3 h/d by final 3 weeks of traninig protocol. In this duration, C group didn't receive any intervention. One day after the end of training protocol, blood samples of rats were obtained on vena cava. The activity of lactate dehydrogenase (LDH) and creatine kinase (CK) was measured with DGKC method and malondialdehyde (MDA) through reaction with TBA. Results were analyzed using the one- way ANOVA followed by a Tukey test. Significant level was 0.05.

Results: EN groups significantly increased the levels of CK compared with EX and C groups (p=0.001), when indicated significantly lesser levels of MDA than C group (p=0.011). But, no significantly difference observed in the levels of LDH.

Conclusion: It seems that endurance swimming creates more muscle damage, while were generates lesser lipid peroxidation.