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Arginine and Ornithine

In a recent study published in the Journal of Strength &
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Conditioning Research, scientists from Poland have shown that taking an arginine and ornithine supplement during heavy resistance training significantly elevates growth hormone (GH) and insulin-like growth factor-1 (IGF-1). Using a placebo controlled, double blinded design, 17 college aged athletes ( bodybuilders and weight lifters) were divided into experimental and control groups and placed on the same diet and training schedule. Subjects ingested 2.2 grams of ornithine and 3.0 grams of L-arginine or placebo twice daily (1 hour before training and 30 minutes before bed) for 3 weeks while completing an intense lower body weight-training program. Blood samples were taken at rest, 2 minutes after training, and after 1 hour of recovery at the onset and end of the training program to test for cortisol, testosterone, GH, IGF-1, Insulin-like growth factor binding protein-3 (IGFBP-3), and insulin levels. The researchers reported no differences in hormone levels at baseline and that all measures were elevated by exercise at both time points. Remarkably, those subjects who ingested arginine and ornithine saw about a 25% increase in blood GH and IGF-1 levels over the other groups!

Zajac A, Poprzecki S, Zebrowska A, Chalimoniuk M, Langfort J. Arginine and ornithine supplementation increases growth hormone and insulin-like growth factor-1 serum levels after heavy-resistance exercise in strength-trained athletes. J Strength Cond Res. 2010 Apr;24(4):1082-90.