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L-arginine does not improve biochemical and hormonal response in trained runners after 4 weeks of supplementation.
- Source :
-
Nutrition research (New York, N.Y.) [Nutr Res] 2014 Jan; Vol. 34 (1), pp. 31-9. Date of Electronic Publication: 2013 Oct 18. - Publication Year :
- 2014
-
Abstract
- It has been hypothesized that L-arginine improves exercise performance by increasing nitric oxide synthesis and levels of insulin and growth hormone (GH). Metabolic and hormonal responses to chronic L-arginine supplementation may clarify the mechanisms underlying its putative physiologic effects on physical performance. Therefore, the aim of this study was to investigate the effects that 4 weeks of supplementation with L-arginine would have on metabolic and hormonal parameters at rest and in response to exercise. Fifteen healthy runners were divided into treatment (ARG; 6 g L-arginine) and placebo (PLA; 6 g cornstarch) groups. On the first visit, blood samples were collected for baseline, and the supplement or placebo was provided. After 4 weeks of supplementation (second visit), blood samples were collected at the following intervals: at rest, immediately after the first 5-km time-trial running test (5km-TT), immediately after the second 5km-TT, and after 20 minutes of recovery (+20). In addition to exercise performance (total running time), plasma nitrate, nitrite, nitrate plus nitrite, cyclic guanosine monophosphate, lactate, ammonia and serum insulin, GH, insulin-like growth factor 1, and cortisol concentrations were evaluated. There were significant increases in plasma nitrite, cyclic guanosine monophosphate, lactate, ammonia and serum GH, and cortisol at the first 5km-TT, immediately after the second 5km-TT, and +20 in both ARG and PLA. Nitrate plus nitrite and nitrate increased only at +20. No significant change was observed in serum insulin and insulin-like growth factor 1 in any sample period. Total running time did not differ significantly between the 2 tests, in either ARG or PLA. Thus, according to our results, 4 weeks of L-arginine supplementation did not cause beneficial changes in metabolic and hormonal parameters, beyond those achieved with exercise alone.<br /> (© 2013.)
- Subjects :
- Adult
Ammonia blood
Cyclic GMP blood
Dietary Supplements
Double-Blind Method
Female
Human Growth Hormone blood
Humans
Hydrocortisone blood
Insulin blood
Insulin-Like Growth Factor I analysis
Lactic Acid blood
Male
Nitrates blood
Nitric Oxide biosynthesis
Nitrites blood
Placebos
Arginine administration & dosage
Exercise physiology
Hormones blood
Running physiology
Subjects
Details
- Language :
- English
- ISSN :
- 1879-0739
- Volume :
- 34
- Issue :
- 1
- Database :
- MEDLINE
- Journal :
- Nutrition research (New York, N.Y.)
- Publication Type :
- Academic Journal
- Accession number :
- 24418244
- Full Text :
- https://doi.org/10.1016/j.nutres.2013.10.006