Acute amino acids supplementation enhances pituitary responsiveness in athletes

Med Sci Sports Exerc. 1999 Dec;31(12):1748-54. doi: 10.1097/00005768-199912000-00009.


Purpose: The purpose of this study was to determine the effect of a mixture of amino acids on pituitary responsiveness to a stimulation test (GnRH + CRH) in athletes.

Methods: In a double blinded counterbalanced experimental protocol, 10 moderately trained male athletes performed the pituitary stimulation test 60 min after a single oral administration of a placebo (P1-AS) or an amino acid mixture solution (AS) (L-arginine hydrochloride 100 mg x kg(-1) + L-ornithine hydrochloride 80 mg x kg(-1) + L-branched chain amino acids 140 mg x kg(-1): 50% L-leucine, 25% L-isoleucine, 25% L-valine) on two different occasions. Plasma ACTH, LH, FSH, GH, and cortisol were evaluated before (-60, -30, 0 min) and after (+15, +30, +45, +60, +90 min) the stimulation test.

Results: The ACTH, LH and FSH response to CRH + GnRH was significantly higher in AS group both as absolute values and area under curve (AUC) values than in P1-AS group. Pre-test and post-test cortisol AUC levels were significantly higher in P1-AS group although a higher percent increase in post-test cortisol was found in AS group. The total GH-AUC was higher in AS group and, as expected, the absolute GH concentrations at different time points were not influenced by CRH + GnRH administration.

Conclusion: The amino acid mixture used enhanced the ACTH, LH, and FSH response to CRH + GnRH.

Publication types

  • Clinical Trial
  • Controlled Clinical Trial

MeSH terms

  • Adrenocorticotropic Hormone / blood
  • Adult
  • Amino Acids / administration & dosage*
  • Corticotropin-Releasing Hormone / pharmacology
  • Dietary Supplements*
  • Follicle Stimulating Hormone / blood
  • Human Growth Hormone / blood
  • Humans
  • Hydrocortisone / blood
  • Hypothalamo-Hypophyseal System / drug effects
  • Luteinizing Hormone / blood
  • Male
  • Pituitary Gland / physiology*
  • Pituitary-Adrenal System / drug effects
  • Sports / physiology*


  • Amino Acids
  • Human Growth Hormone
  • Adrenocorticotropic Hormone
  • Luteinizing Hormone
  • Follicle Stimulating Hormone
  • Corticotropin-Releasing Hormone
  • Hydrocortisone