Background and Aims: Post exercise proteinuria and increased urinary Gamma-Glutamyl transferase (GGT) levels can be indicative of exercise-induced renal damage. The aim of this investigation was to study the effect of one session of intensive training on renal tubular injury markers and compare their values to those 6 hours after training, for evaluating tubular damage after intensive training. Materials and Methods: In this cross-sectional study with pre- and post- test design, 10 elite volunteer male athletes were selected and participated in one training session (2 hours). Urine samples were collected before training, one hour after training, and 6 hours after training. Urinary protein, creatinine, and GGT values were measured through laboratory methods and then Pr/Cr and GGT/Cr ratios were computed. Results: There were significant differences between values of protein, urine Pr/Cr ratio, GGT and creatinine in the three sampling phases (P<0.05). However, no significant differences were observed between values for GGT/Cr ratio. There were significant differences between the mean values of creatinine, protein, GGT, and Pr/Cr ratio within pre-exercise and 1 hour post-exercise values and Pr/Cr ratio values in pre-exercise and 6 hours post-exercise (P<0.05). Conclusions: It seems that a session of karate training does not result in permanent renal damage and for evaluation of tubular function, it is better to get the urine sample for urinary marker at least 6 hours after exercise
