Background: Many studies have focused on the effect of L-arginine supplementation on physical performance and blood lactate level, however, the obtained results are contradictory. The aim of present study was to determine the effect of L-arginine supplementation on blood lactate level and VO2 max at anaerobic threshold among the athletes in Tehran-Iran.

Materials & Methods: Thirty healthy male athletes (age: 22.66±1.46) were randomly divided into two groups based on a blind placebo-controlled trial. Subjects performed the exercise test before and after the intake of L-arginine (5 g/day) or placebo for a period of 3 weeks. The exercise tests were carried out on treadmill until the anaerobic threshold (according to Conconi protocol) was reached. In each trial, three blood samples (before, at the end and 30 minutes after the completion of exercise) were obtained.

Results: Blood lactate level was significantly decreased in the L-arginine group compared to the placebo one. There was no significant difference between the two groups in VO2 max at anaerobic threshold. Only in the L-arginine group, VO2 max at anaerobic threshold was significantly increased. In addition, there was no significant difference in VO2 max at anaerobic threshold for the placebo group.

Conclusion: Oral supplementation of L-arginine decreases blood lactate level and may have beneficial effects on muscular fatigue. L-arginine not effectively had no influence on VO2 max at anaerobic threshold. Thus, it can be concluded that the dosage used is unable to increase the VO2 max at anaerobic threshold.