Introduction: Sports activities with increased mechanical pressure can lead to biochemical changes in the body. The purpose of this study was to investigate the effect of one session of exhaustive swimming training on the response of creatine kinase (CK), lactate dehydrogenase (LDH), and lactate in elite male swimmers. Methods: In this experimental study, 28 elite male swimmers aging 15-20 years in Fars province who were performing their training every day at Enghelab International Pool of Shiraz were selected as the sample of study. At first, the health status form and informed consent questionnaire were completed by athletes and their parents. To eliminate the effect of previous training on levels of LDH, CK and lactate, a 48-hour rest before the implementation of the research protocol was given to swimmers. On the day of the research, blood samples were taken before training in the sitting position. The swimmers then warmed up for 10 minutes. Subsequently, all subjects performed exhaustive swimming training. Immediately after the end of the training, 15 and 30 minutes following the training, blood samples were again taken from all of the subjects similarly in the sitting position. To analyze the findings of the research, repeated measures ANOVA along with Bonferroni’s post hoc test were used at p≤0.05. Results: One session of exhaustive swimming training did not have a significant effect on CK of elite male swimmers (P = 0.40); one session of exhaustive swimming training had a significant effect on LDH (P = 0.001) and lactate (P = 0.001) of elite male swimmers; LDH levels decreased significantly 15 minutes (P = 0.001) and 30 minutes (P = 0.009) after training, and lactate levels decreased significantly 30 minutes after training (P = 0.001). Conclusion: It seems that one session of exhaustive swimming training in elite male swimmers leads to a significant increase in LDH and lactate. Also, LDH decreases significantly after 15 minutes and lactate after 30 minutes. Manuscript profile