Low-dose amino acid supplementation: no effects on serum human growth hormone and insulin in male weightlifters.
Using a double-blind, crossover protocol, we studied the possible effects of a 4-day combined L-arginine, L-ornithine, and L-lysine supplementation (each 2 g/day, divided into two daily doses) on 24-hr level of serum human growth hormone (hGH) and insulin in 11 competitive weightlifters, ages 19 to 35 yrs. Three similar daily hGH peaks, seemingly preceded by a decrease in serum insulin concentration, were found during both amino acid and placebo supplementation. Supplementation did not affect the physiological variation of serum hGH concentration (treatment and treatment x time interaction: p = 0.43-0.55). Analogously, serum insulin levels were not higher after amino acid supplementation. Therefore the ergogenic value of low-dose oral amino acid supplementation in increasing hGH or insulin secretion seems questionable.
Fogelholm
G M
GM
Dept. of Applied Chemistry and Microbiology, University of Helsinki, Finland.
Näveri
H K
HK
Kiilavuori
K T
KT
Härkönen
M H
MH
D000328:Adult; D000596:Amino Acids / Q000008:administration & dosage / Q000494:pharmacology*; D004311:Double-Blind Method; D004334:Drug Administration Schedule; D013006:Growth Hormone / Q000097:blood / Q000187:drug effects*; D006801:Humans; D007328:Insulin / Q000378:metabolism; D008297:Male; D014891:Weight Lifting / Q000502:physiology*
D000596:Amino Acids; D007328:Insulin; D013006:Growth Hormone