FAILURE OF COMMERCIAL ORAL AMINO-ACID SUPPLEMENTS TO INCREASE SERUM GROWTH-HORMONE CONCENTRATIONS IN MALE BODY-BUILDERS

Amino acids are commonly ingested as ergogenic aids in the belief that they enhance protein synthesis and stimulate growth hormone release. The aim of this study was to determine the acute effect that amino aci d supplements have on serum growth hormone (GH) concentration. Seven m ale body-builders reported to the laboratory on four occasions after a n 8-hr fast and ingested, in random order, either a placebo, a 2.4-g a rginine/lysine supplement, a 1.85-g ornithine/tyrosine supplement, or a 20-g Bovril(R) drink. Blood was collected before each treatment and again every 30 minutes for 3 hours for the measurement of serum GH con centration. On a separate occasion, subjects had an intravenous infusi on of 0.5 mug GH-releasing hormone.kg-1 body weight to confirm that GH secretory response was normal. The main finding was that serum GH con centrations were not altered consistently in healthy young males follo wing the ingestion of the amino acid supplements in the quantities rec ommended by the manufacturers.