The Effects of Supplementary L-Arginine Dietary on Serum Nitric Oxide Concentration in the Male Bodybuilders

Aim: Arginine has been classified as a 'semi-essential' or 'conditionally essential' amino acid. This characterization alludes to the fact that arginine has to be extracted from the diet as a supplement to the endogenous synthesis in growing mammals and in adult animals or humans during disease or trauma; however, arginine can be synthezised in sufficient quantity in the healthy adult. The aim of this study was to investigate the effect of long term arginine supplementation on Nitric oxide in intermittent anaerobic exercise and the underlying mechanism in well-trained male bodybuilders. Method: 30 elite male bodybuilder athletes recruited from The clubs of bodybuilding of Tehran participated in this Study. The subjects were 21.5 +/- 0.3 years old. The height were 1.71 +/- 0.06 m. The body weight in arginine (ARG) and control (CON) trials were 69.4 +/- 3.8 and 71.3 +/- 1.0 kg, respectively. This study used a randomized cross-over, placebo controlled design. Each subject was randomly assigned to ARG or CON trial separated.ARG trial consumed 12 g/day arginine tablets for 6 weeks. Result: No significant difference was found between the 2 trials at any time point. In both trials, NOx concentration was significantly higher during and 6 min after exercise comparing to the basal concentration. This study suggested that the long-term supplementation of arginine had no effect on plasma NO in intermittent anaerobic tests in well-trained male athletes. The use of arginine supplementation to increase NO production, reduce metabolites accumulation and improve exercise performance in athletes should be critically reevaluated even though it may have beneficial effect in certain patients and general population.