Best Pre-Workout Ingredients for Muscle Pumps
by: Robbie Durand
L-arginine is an amino acid obtained from the diet and is necessary for the body to form proteins. L-arginine is found in red meat, poultry, fish, and dairy products. It is converted in the body into a chemical called nitric oxide, which causes blood vessels to open wider for improved blood flow. L-arginine also stimulates the release of several anabolic hormones such as growth hormone, insulin, and other substances in the body.
The vasodilator effect of l-arginine has been well documented. The body uses l-arginine to produce nitric oxide (NO), a very important component for any pre-workout supplement to any bodybuilder.
Researchers from Brazil tested the specific acute effects of pre-workout l-arginine supplementation of NO production, as well as muscle blood volume and oxygenation during recovery from three sets of heavy resistance exercise. In a randomized, double-blind and placebo-controlled study 15 healthy college-age male participants were given either 6 grams of L-arginine or a placebo, which they took 30 minutes before performing biceps curls (3 sets of 10 reps) at maximum voluntary contraction. Blood samples were taken before supplementation and periodically for two hours post-supplementation.
The researchers reported that, compared to the placebo group, acute arginine supplementation increased muscle blood volume by greater than 100% during recovery from each set of biceps curls. They noted no measurable differences in muscle oxygenation or strength performance between groups. L-arginine works synergistically with citrulline to enhance muscle vasodilation. Another amino acid with potent vasodilatory effects is citrulline.
L-Citrulline is a colorless, water-soluble α-amino acid that is a potent endogenous precursor of l-arginine. Thus, l-citrulline supplementation has been shown to exhibit several beneficial effects on the cardiovascular system. Citrulline works in conjunction with L-arginine to enhance muscle blood flow.
In a recent clinical study, l-citrulline supplementation dose-dependently increased plasma l-arginine levels in healthy human volunteers more effectively than equivalent doses of l-arginine itself. Furthermore, other researchers have demonstrated in clinical trials that l-citrulline supplementation functionally improves arterial stiffness, meaning it improved blood vessel dilation. So both work synergistically together but what according to research, combining the two work better than each one separately.
In a previous study, Japanese researchers published an animal study in which they showed that a combination of L-arginine and L-citrulline offered the animals’ blood vessels better protection against atherosclerosis than L-arginine alone or L-citrulline alone. This means that both arginine and citrulline worked better combined than either one alone.
The researchers gave rabbits water containing a 12 grams of arginine. A second group of rabbits was given an identical dose of L-citrulline, and a third group was given a mixture containing equal amounts of L-arginine and L-citrulline. The human equivalent of the doses that the third group of rabbits got would be about 6 grams L-arginine and 6 grams L-citrulline. Forty-five minutes after receiving the supplements the animals’ circulation improved. The effect of the mixture was greater than that of the amino acids when given separately. The major findings of the study was that a combination of oral l-citrulline and l-arginine effectively and rapidly increases plasma l-arginine and enhances NO-dependent responses, particularly within 1 h after supplementation.
A noteworthy finding in the study was that a rapid increase in plasma l-arginine levels was observed with a combination of oral l-citrulline plus l-arginine than for a single amino acid. Interestingly, previous research has demonstrated that l-citrulline suppresses arginase activity (i.e. arginase blocks NO production). The mixture of L-citrulline and L-arginine resulted in a bigger rise in the concentration of NO in the blood of the animals than the rise of the amino acids separately.
Biochem Biophys Res Commun. 2014 Oct 14;454(1):53-57.
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