Frey, W. O., Bitzi, R., Arnold, M., Langhans, W., Wank, C., & Frey-Rindova, P. (1999). Arginine aspartate supplementation in marathon runners reduces total plasma amino acid level. Medicine and Science in Sports and Exercise, 31(5), Supplement abstract 706.

The metabolic influence of a 14-day supplementation to normal diet with L-arginine-L-aspartate (15 g/day) was investigated in endurance trained athletes (N = 14) during a non-competitive marathon run.

The supplementation had no effect on running time. Metabolic effects were observed from supplementation. Since the effects of those effects are not known in humans, the practice of using single amino acid supplementation as a potential ergogenic aid should be critically evaluated.

Implication. Amino acid supplementation in athletes should not be undertaken until more research determines the effects of the procedure.

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