L-Arginine Supplementation Enhances Exercise Tolerance?
In a recent study that included just 9 recreationally active males, researchers studied the effect of acute ingestion of l-arginine supplementation on high-intensity exercise tolerance (Bailey et al, 2010). L-arginine is an amino acid.
The subjects who were between the ages of 19-38 years of age consumed a beverage either consisting of 6g of l-arginine or placebo 1 hour prior to completely moderate to high-intensity exercise bouts on a cycling ergometer.
“Participants received a 20 g dose of the 163 ARK 1 supplement which contained 6 g L-arginine along with trace amounts of vitamins (E, C, B6 and B12), other amino acids (L-glutamine, L-leucine, L-valine, L-carnitine, L-citrulline, L-cysteine and L-isoleucine), and fructose (11 g) at a dose that would not be expected to elicit performance gains.”
- Plasma nitrate was significantly higher following l-arginine supplementation compared to placebo (ARG: 331 +/- 198 vs. PLA: 159 +/- 102 nM; P<0.05)
- Systolic blood pressure was significantly lower following l-arginine supplementation compared to placebo (ARG: 123 +/- 3 vs. PLA: 131 +/- 5 mmHg; P<0.01)
- Steady-state VO(2) during moderate-intensity exercise was reduced by 7% in the l-arginine group (ARG: 1.48 +/- 0.12 vs. PLA: 1.59 +/- 0.14 L*min(-1); P<0.05).
“During severe-intensity exercise, the VO(2) slow component amplitude was reduced (ARG: 0.58 +/- 0.23 vs. PLA: 0.76 +/- 0.29 L*min(-1); P<0.05) and the time-to-exhaustion was extended (ARG: 707 +/- 232 s vs. PLA: 562 +/- 145 s; P<0.05) following ARG.”
Study Author Conclusions:
“Acute dietary supplementation with 6 g L-arginine, which increased indices of NO synthesis, reduced the steady-state O2 during moderate-intensity exercise, and also reduced the O2 slow component and increased the time to task failure during severe intensity exercise in healthy adults.”
What Does This Mean?
From the researchers:
“During moderate intensity exercise, pulmonary oxygen update V0(2) increases exponentially until it reaches a steady state after two to three minutes. Steady-state VO(2) or pulmonary oxygen update reflects the rate of ATP turnover in the myocytes (muscle cells) which is directly related to the external work load (exercise intensity).”
During high-intensity exercise, muscle contractility progressively declines during which a V0(2) slow component is apparent. The V0(2) slow component delays the attainment of a steady-state and sets the V0(2) on a trajectory towards its maximum [V0(2) peak]. Interventions that reduce the amplitude of the V0(2) slow component reportedly improve severe-intensity exercise tolerance.
In short, this recent study suggests that a diet rich in l-arginine improves exercise efficiency and exercise tolerance in healthy males.
- Bailey SJ, Winyard PG, Vanhatalo A, Blackwell JR, Dimenna FJ, Wilkerson DP, Jones AM. Acute L-arginine supplementation reduces the O2 cost of moderate-intensity exercise and enhances high-intensity exercise tolerance. J Appl Physiol. 2010 Aug 19.
Jarret Morrow, M.D.
Hi Ileane, from what I understand, it's not currently one of the ingredients in AMP or other major energy drinks. L-arginine is included in an energy drink from BSN called Endorush. However, BSN doesn't list the quantity of l-arginine in their product. It is available at most vitamin and supplement stores if you're interested though.
Jarret Morrow, M.D.
Hi K.L., I should have clarified to Ileane in regards to my comment about l-arginine being widely available--I meant as a dietary supplement and not specifically referring to the beverage from BSN.
Two questions: 1. Which is the best food to eat to increase intake of this particular protein and is its absorbtion enhanced by the presence of any other food? 2. Taking in too much protein (acid) canlead to osteoporosis, as the body leeches the bones for alkalinity to maintain the necessary pH level. What's your advice on this?
Jarret Morrow, M.D.
Hi Liz, thanks for your questions. In terms of supplementation with l-arginine, I would image that people would do this on a short-term basis as opposed to longer term. Food sources high in arginine would mostly include various types of nuts, and meat, milk, and soy protein to a lesser degree. I'm not sure that the effects would be equivalent. It's a non-essential amino acid which means that you're body can synthesize it. Studies on the pharmacokinetics of l-arginine taken as an oral supplement have shown bioavailabilities ranging from 20-70%. It's typically taken on an empty stomach with water and I'm not aware of anything enhancing its absorption. As to your second question, if someone is concerned about too much dietary protein leading to osteoporosis... the simple answer is to avoid taking in too much protein. :p On a more serious note, some recent studies have questioned suggested the opposite effect: http://www.ncbi.nlm.nih.gov/pubmed/20717017 http://www.ncbi.nlm.nih.gov/pubmed/20883419
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Hi Jarret, where can I get some?? Do they add it to energy drinks like AMP? Thanks for the info.