J Strength Cond Res. 2010 Mar 17. [Epub ahead of print]
Arginine and Ornithine Supplementation Increases Growth Hormone and Insulin-Like Growth Factor-1 Serum Levels After Heavy-Resistance Exercise in Strength-Trained Athletes.
Zajac A, Poprzęcki S, Zebrowska A, Chalimoniuk M, Langfort J.
1Department of Sports Training, Academy of Physical Education, Katowice, Poland; 2Department of Biochemistry, Academy of Physical Education, Katowice, Poland; 3Department of Physiology, Academy of Physical Education, Katowice, Poland; 4Department of Cellular Signaling, Mossakowski Medical Research Center, Polish Academy of Sciences, Warsaw, Poland; and 5Department of Experimental Pharmacology, Mossakowski Medical Research Center, Polish Academy of Sciences, Warsaw, Poland.
Zajac, A, Poprzecki, S, Zebrowska, A, Chalimoniuk, M, and Langfort, J. Arginine and ornithine supplementation increases GH and serum levels after heavy-resistance exercise in strength-trained athletes. J Strength Cond Res 24(x): 000-000, 2010-This placebo-controlled double-blind study was designed to investigate the effect of arginine and ornithine (arg and orn) supplementation during 3-week heavy-resistance training on serum growth hormone/insulin-like growth factor-1/insulin-like growth factor-binding protein 3 (GH/IGF-1/IGFBP-3), testosterone, cortisol, and insulin levels in experienced strength-trained athletes. The subjects were randomly divided between a placebo group (n = 8) and the l-Arg/l-Orn-supplemented group (n = 9), and performed pre and posttraining standard exercise tests with the same absolute load, which consisted of the same exercise schedule as that applied in the training process. Fasting blood samples were obtained at rest, 2 minutes after the cessation of the strength exercise , and after 1 hour of recovery. The resting concentrations of the investigated hormones and IGFBP-3 did not differ significantly between the study groups. In response to exercise test, all the hormones were elevated (p < 0.05) at both time points. Significant increases (p < 0.05) were observed in both GH and IGF-1 serum levels after arg and orn supplementation at both time points, whereas a significant decrease was seen in IGFBP-3 protein during the recovery period. Because there was no between-group difference in the remaining hormone levels, it appears that the GH/IGF-1/IGFBP-3 complex may be the major player in muscle tissue response to short-term resistance training after arg and orn supplementation.
J Int Soc Sports Nutr. 2010 Mar 23;7(1):13. [Epub ahead of print]
Arginine and antioxidant supplement on performance in elderly male cyclists: a randomized controlled trial.
Chen S, Kim W, Henning SM, Carpenter CL, Li Z.
ABSTRACT: BACKGROUND: Human exercise capacity declines with advancing age. These changes often result in loss of physical fitness and more rapid senescence. Nitric oxide (NO) has been implicated in improvement of exercise capacity through vascular smooth muscle relaxation in both coronary and skeletal muscle arteries, as well as via independent mechanisms. Antioxidants may prevent nitric oxide inactivation by oxygen free radicals. The purpose of this study was to investigate the effects of an and antioxidant supplement on exercise performance in elderly male cyclists. METHODS: This was a two-arm prospectively randomized double-blinded and placebo-controlled trial. Sixteen male cyclists were randomized to receive either a proprietary supplement (Niteworks(R), Herbalife International Inc., Century City, CA) or a placebo powder. Exercise parameters were assessed by maximal incremental exercise testing performed on a stationary cycle ergometer using breath-by-breath analysis at baseline, week one and week three. RESULTS: There was no difference between baseline exercise parameters. In the supplemented group, anaerobic threshold increased by 16.7% (2.38 +/- 0.18 L/min, p<0.01) at week 1, and the effect was sustained by week 3 with a 14.2% (2.33 +/- 0.44 L/min, p<0.01). In the control group, there was no change in anaerobic threshold at weeks 1 and 3 compared to baseline (1.88 +/-0.20 L/min at week 1, and 1.86 +/- 0.21 L/min at week 3). The anaerobic threshold for the supplement groups was significantly higher than that of placebo group at week 1 and week 3. There were no significant changes noted in VO2 max between control and intervention groups at either week 1 or week 3 by comparison to baseline. CONCLUSION: An arginine and antioxidant-containing supplement increased the anaerobic threshold at both week one and week three in elderly cyclists. No effect on VO2 max was observed. This study indicated a potential role of L-arginine and antioxidant supplementation in improving exercise performance in elderly.