Die dazugehörige Studie dürfte folgende sein:

J Appl Physiol. 2006 Sep;101(3):848-52. Epub 2006 Jun 1.

Oral arginine attenuates the growth hormone response to resistance exercise.

Collier SR, Collins E, Kanaley JA.
Dept. of Exercise Science, Syracuse University, Syracuse, NY 13244, USA.

This study investigated the combined effect of resistance exercise and arginine ingestion on spontaneous growth hormone (GH) release. Eight healthy male subjects were studied randomly on four separate occasions [placebo, arginine (Arg), placebo + exercise (Ex), arginine + exercise (Arg+Ex)]. Subjects had blood sampled every 10 min for 3.5 h. After baseline sampling (30 min), subjects ingested a 7-g dose of arginine or placebo (blinded, randomly assigned). On the exercise days, the subject performed 3 sets of 9 exercises, 10 repetitions at 80% one repetition maximum. Resting GH concentrations were similar on each study day. Integrated GH area under the curve was significantly higher on the Ex day (508.7 +/- 169.6 min.ng/ml; P < 0.05) than on any of the other study days. Arg+Ex (260.5 +/- 76.8 min.ng/ml) resulted in a greater response than the placebo day but not significantly greater than the Arg day. The GH half-life and half duration were not influenced by the stimulus administered. The GH secretory burst mass was larger, but not significantly, on the Arg, Ex, and Arg+Ex day than the placebo day. Endogenous GH production rate (Ex > Arg+Ex > Arg > placebo) was greater on the Ex and Arg+Ex day than on the placebo day (P < 0.05) but there were no differences between the Ex and Arg+Ex day. Oral arginine alone (7 g) stimulated GH release, but a greater GH response was seen with exercise alone. The combined effect of arginine before exercise attenuates the GH response. Autonegative feedback possibly causes a refractory period such that when the two stimuli are presented there will be suppression of the somatotrope.
Danach it die GH-Antwort nach dem Training geringer, wenn man zum Training Arginin konsumiert - aber nur dann.
Arginin ohne Training (auf leeren Magen genommen) zieht eine signifikante GH-Ausschüttung nach sich:
Growth Horm IGF Res. 2005 Apr;15(2):136-9.

Growth hormone responses to varying doses of oral arginine.

Collier SR, Casey DP, Kanaley JA.
Department of Exercise Science, Syracuse University, 820 Comstock Avenue, Room 201, Syracuse, NY 13244, USA.

Intravenous (IV) arginine invokes an increase in growth hormone (GH) concentrations, however, little is known about the impact of oral arginine ingestion on the GH response. OBJECTIVE: The purpose of this study was to determine the dose of oral arginine that elicits an optimal GH response and to determine the time course of the response. DESIGN: Eight healthy males (18-33 years - 24.8+/-1.2 years) were studied on 4 separate occasions. Following an overnight fast at 0700 h, a catheter was placed in a forearm vein. Blood samples were taken every 10 min for 5 h. Thirty minutes after sampling was initiated, the subject ingested a dose of arginine (5, 9 or 13 g) or placebo (randomly assigned). RESULTS: Mean resting GH values for the placebo, 5, 9 and 13 g day were 0.76, 0.67, 2.0 and 0.79 microg/L (n=6), respectively. Integrated area under the curve was not different with 13 g (197.8+/-65.7 min microg/L), yet it increased with 5 and 9 g compared with the placebo (301.5+/-74.6, 524.28+/-82.9 and 186.04+/-47.8 min microg/L, respectively, P<0.05). Mean peak GH levels were 2.9+/-0.69, 3.9+/-0.85, 6.4+/-1.3 and 4.73+/-1.27 microg/L on each day for the placebo, 5, 9 and 13 g days. CONCLUSION: In conclusion, 5 and 9 g of oral arginine caused a significant GH response. A 13 g dose of arginine resulted in considerable gastrointestinal distress in most subjects without augmentation in the GH response. The rise in GH concentration started approximately 30 min after ingestion and peaked approximately 60 min post ingestion.
Folglich kann Arginin die GH-Werte erhöhen als auch verringern - ja nachdem unter welchen Umständen es genommen wird.