L-arginine and L-ornithine are two amino acids that are available as sports supplements. L-arginine is a conditionally essential amino acid -- the body can generally synthesize it from other amino acids, except in preterm infants and in trauma patients. Arginine is important for wound healing and is the precursor of the signalling molecule nitric oxide and the amino acid ornithine. The latter is important for the disposal of excess nitrogen.
Growth Hormone
A study reported in the April 2010 issue of the “Journal of Strength and Conditioning Research” investigated the effects of three weeks of arginine and ornithine supplementation on hormone levels. The study found that in response to a strength-training session, all hormones tested -- growth hormone, insulin-like growth factor-1, testosterone, cortisol and insulin -- were elevated. It was also found that in the group given 3,000 mg of arginine and 2,200 mg of ornithine twice daily, growth hormone and insulin-like growth factor-1 were higher than in the group given the placebo.
Anaerobic Performance
Ornithine hydrochloride supplementation at 0.2 g per kilogram of body mass increased anaerobic performance, reported the March 2011 issue of the “European Journal of Applied Physiology.” The test was carried out using a cycle ergometer. The study found that following ornithine hydrochloride supplementation, blood levels of ornithine were elevated. However, the mechanism behind the improvement in performance was unclear.
Fatigue
A placebo-controlled study reported in the November 2010 issue of the “Journal of Applied Physiology” found that supplementing adult healthy males with 6 g of arginine before exercise delayed exhaustion. This was due to a reduced oxygen cost of exercise, possibly through an enhanced vascular function brought about by higher levels of nitric oxide production. The study also found that arginine supplementation significantly reduced systolic blood pressure.
Antioxidant
Intense exercise results in significant oxidative and inflammatory stress on the body; the stress will be higher in the elderly. Arginine supplementation in aging rats protected against oxidative damage and inflammation, according to a study published in the June 2008 issue of “Experimental Gerontology.” Arginine was also found to prevent the exercise-induced increases in blood lactate and uric acid levels in aging rats and to increase exercise capacity.
References
- “Journal of Strength and Conditioning Research”; Arginine and Ornithine Supplementation Increases Growth Hormone and Insulin-Like Growth Factor-1 Serum Levels After Heavy-Resistance Exercise in Strength-Trained Athletes; A. Zajac, et al.; April 2010
- “European Journal of Applied Physiology”; Effect of L: -Ornithine Hydrochloride Ingestion on Intermittent Maximal Anaerobic Cycle Ergometer Performance and Fatigue Recovery After Exercise; S. Demura, et al.; March 2011
- “Journal of Applied Physiology”; Acute L-Arginine Supplementation Reduces the O2 Cost of Moderate-Intensity Exercise and Enhances High-Intensity Exercise Tolerance; S.J. Bailey, al el.; November 2010
- “Experimental Gerontology”; Potential Ergogenic Effects of L-Arginine Against Oxidative and Inflammatory Stress Induced by Acute Exercise in Aging Rats; C.C. Huang, et al.; June 2008
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