Growth Hormone Release L-Arginine Muscle Gain

L-Arginine – Mixed results on ergogenic effect, boost GH at rest

L-arginine is a conditionally essential amino acid and it plays an important role in cell division, immune function, release of hormones and wound healing [1,2]. Arginine is the immediate precursor of nitric oxide (NO), urea, ornithine, and agmatine, it is also necessary for the synthesis of creatine.[1] It is found in red meat, poultry, fish, and dairy products.

L-Arginine as Performance Enhancer

L-arginine is broadly marketed (usually as arginine alphaketoglutarate [AAKG]) in order to promote widening of blood vessels by increasing nitric oxide (NO) production in muscles during exercise, improving strength, power and muscular recovery. However studies contrast each other [3]. Many studies show no significant results with L-arginine as performance enhancer [4-8] while some show beneficial effects [9-11].

Two more recent studies [20,21] both reported no effect of L-arginine on exercise performance or recovery in healthy individuals. Furthermore, L-arginine supplementation was unable to increase the effects of exercise on nitric oxide production in runners [22].

L-arginine supplementation only seems to aid in nitric oxide synthesis when body is in L-arginine deficiency [12].

Effects on Human Growth Hormone

Orally supplemented L-arginine has been shown to cause a significant increment in resting growth hormone levels (by at least 100%) at doses from 5-9 grams [14]. A higher dose of 13 grams did not augment growth hormone response, probably due to intestinal distress which prevented absorption of the L-arginine [14]. In contrast to this study, Forbes and Bell [17] reported that neither high nor low dose or orally supplemented L-arginine was able to promote a significant increase in IGF-1, growth hormone, nitric oxide or insulin at rest.

A study measuring 24 hour growth hormone secretion reported no significant differences with two daily doses of 2 g [18]. This may be explained by modulatory effect on growth hormone known as auto-negative feedback loop.

Both exercise and L-arginine have both been shown to independently augment growth hormone concentrations; however, their combined effect is controversial. The combination of oral arginine and exercise was reported to attenuated the growth hormone spike caused by exercise alone [13,15]. Exercise alone can increase growth hormone levels by 300-500%, while oral L-arginine plus exercise only increased growth hormone levels by around 200% [13]. This diminished response is seen in both younger and older individuals [14]; however, it seem to affect youth more than older persons [15].

In support to these findings, a more recent study by Forbes et al. [19] reported that L-arginine ingested prior resistance training attenuated plasma growth hormone in bodybuilders. Researchers also noted that growth hormone suppression was not due to a growth hormone or IGF-1 induced auto-negative feedback loop.

Possible L-Arginine Side Effects

Low oral doses are well tolerated and clinical side effects are rare in healthy subjects [3]. At high doses (13 grams) arginine was reported to cause considerable gastrointestinal distress [14]. Other side effects may include low blood pressure, diarrhea, abdominal pain,..

References

  1. Tapiero, H.; et al. (November 2002). “L-Arginine”. Biomedicine and Pharmacotherapy 56 (9): 439–445 Review
  2. Witte, Maria B., and Adrian Barbul. “Arginine physiology and its implication for wound healing.” Wound repair and regeneration 11.6 (2003): 419-423.
  3. Alvares, Thiago S., et al. “L-Arginine as a potential ergogenic aid in healthy subjects.” Sports Medicine 41.3 (2011): 233-248.
  4. Abel, Tilo, et al. “Influence of chronic supplementation of arginine aspartate in endurance athletes on performance and substrate metabolism.” Int J Sports Med 26.5 (2005): 344-349.
  5. Wax B, et al. Acute L-arginine alpha ketoglutarate supplementation fails to improve muscular performance in resistance trained and untrained men. J Int Soc Sports Nutr. (2012)
  6. Colombani, P. C., et al. “Chronic arginine aspartate supplementation in runners reduces total plasma amino acid level at rest and during a marathon run.” European journal of nutrition 38.6 (1999): 263-270.
  7. Liu, Tsung-Han, et al. “No effect of short-term arginine supplementation on nitric oxide production, metabolism and performance in intermittent exercise in athletes.” The Journal of nutritional biochemistry 20.6 (2009): 462-468.
  8. Fahs, Christopher A., Kevin S. Heffernan, and Bo Fernhall. “Hemodynamic and vascular response to resistance exercise with L-arginine.” Medicine and science in sports and exercise 41.4 (2009): 773.
  9. Schaefer, A., et al. “L-arginine reduces exercise-induced increase in plasma lactate and ammonia.” International journal of sports medicine 23.6 (2002): 403-407.
  10. Lucotti, Pietro, et al. “Beneficial effects of a long-term oral L-arginine treatment added to a hypocaloric diet and exercise training program in obese, insulin-resistant type 2 diabetic patients.” American Journal of Physiology-Endocrinology And Metabolism 291.5 (2006): E906-E912.
  11. McConell GK. Effects of L-arginine supplementation on exercise metabolism. Curr Opin Clin Nutr Metab Care. (2007)
  12. Lekakis, John P., et al. “Oral L-arginine improves endothelial dysfunction in patients with essential hypertension.” International journal of cardiology 86.2 (2002): 317-323.
  13. Kanaley, Jill A. “Growth hormone, arginine and exercise.” Current Opinion in Clinical Nutrition & Metabolic Care 11.1 (2008): 50-54.
  14. Collier, Scott R., Darren P. Casey, and Jill A. Kanaley. “Growth hormone responses to varying doses of oral arginine.” Growth hormone & IGF research 15.2 (2005): 136-139.
  15. Marcell, Taylor J., et al. “Oral arginine does not stimulate basal or augment exercise-induced GH secretion in either young or old adults.” The Journals of Gerontology Series A: Biological Sciences and Medical Sciences 54.8 (1999): M395-M399.
  16. Collier, S. R., Ellise Collins, and Jill A. Kanaley. “Oral arginine attenuates the growth hormone response to resistance exercise.” Journal of Applied Physiology 101.3 (2006): 848-852.
  17. Forbes, Scott C., and Gordon J. Bell. “The acute effects of a low and high dose of oral L-arginine supplementation in young active males at rest.” Applied Physiology, Nutrition, and Metabolism 36.3 (2011): 405-411.
  18. Fogelholm, G. M., et al. “Low-dose amino acid supplementation: no effects on serum human growth hormone and insulin in male weightlifters.” International journal of sport nutrition 3.3 (1993): 290-297.
  19. Forbes, S. C., V. Harber, and G. J. Bell. “Oral L-Arginine Prior To Resistance Exercise Blunts Growth Hormone in Strength Trained Males.” International journal of sport nutrition and exercise metabolism (2013).
  20. Garcia, A., et al. “The Acute Effects of L-Arginine On Recovery and Resistance Exercise.” International Journal of Exercise Science: Conference Proceedings. Vol. 9. No. 1. 2013.
  21. Vanhatalo, Anni, et al. “No effect of acute l-arginine supplementation on O2 cost or exercise tolerance.” European journal of applied physiology 113.7 (2013): 1805-1819.
  22. dos Santos Baião, Diego, et al. “L-Arginine Supplementation and Nitric Oxide Production: No Additional Effect When Associated to Exercise.” Food & Nutrition Sciences 4.8 (2013).

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