L-Arginine is a conditionally essential amino acid that improves health and performance in athletes. It is a precursor for nitric oxide which improves blood flow. Supplementing with L-Arginine can improve immune function, decrease ammonia levels, and attenuate oxidative stress. Recommendations are to supplement with 400-6,000 mg of L-Arginine per day, either 1-3 times daily depending on the sport and training period. Caution should be taken with individuals with high blood levels of arginine or those taking certain medications due to potential side effects.

1. Miguel Cabezas.Pharmacist.
Sport Molecular Nutrition.
Copyright ©. March 2016.
IMPROVING THE HEALTH OF ATHLETES.
SPORT MOLECULAR NUTRITION.
ARGININE IN INDIVIDUALIZED SUPPLEMENTS PROTOCOLS.
1.GENERAL FEATURES.
L-Arginine (2-amino-5-guanidinovaleric acid) is a conditionally essential amino
acid. Endogenous synthesis meets the need of human body, but in catabolic stress
during training or competition in high performance the novo synthesis becomes
inadequate.
US National Health and Nutrition Examination Survey indicate that mean Arginine
consumption for the US adult population is 4.4 g/day.
Insufficient intake of Arginine may lead to hyperammonemia,
immunosuppresion, altered neurotransmission, impaired recovery,
disturbed inflammatory response and diminished vascular function.

2. The sources of free Arginine within the body are dietary protein, endogenous
synthesis (intestinal renal-axis and liver) and turnover of body proteins (in fasting
state 85 % aprox. of the arginine entering the circulation is derived from protein
turnover). Rates of endogenous novo synthesis of Arginine, its precursors and
derivates vary greatly.
Molecular Nutritionist must consider that 40% of dietary Arginine intake does not
enter the systemic circulation in adults because is degraded by the small intestine
in first pass metabolism.
The rate of endogenous synthesis is independent of Arginine intake.
There are Recommended Daily Allowances for essential amino acids but not for
non essential or semi essential amino acids.
2. BIOCHEMICAL PATHWAYS.
Arginine is a precursor of Urea, Nitric Oxide, Glutamate, Creatine, Agmatine and
Proline.
Arginine improves Protein Synthesis (via mTOR cell pathway).
Four enzymes use Arginine as a substrate: Arginine decarboxylase, Arginine-
Glycine amidinotransferase, Arginase and NOS.

3. Arginine can increase Growth Hormone release, Insulin and Glucagon.
A portion of the Citrulline produced by nitric oxide synyhase (NOS) can be recycled
to Arginine (citrulline–NOcycle). Citrulline is able to increase levels of plasma
Arginine more effective than Arginine itself.
Glutamine is a precursor for the synthesis of Citrulline in the intestines and
Arginine by the kidneys through glutamine-citrulline-arginine intestinal-renal axis.
3.BENEFITS IN HEALTH AND PERFORMANCE OF ATHLETES.
As a precursor of Nitric Oxide (NO. Vasodilator) in the body via the nitric oxide
synthase enzymes improves blood flow.
Reduced Arginine availability (catabolic stress) can selectively affect the
expression of specific genes.
Improvements in immune function.
Decreases high ammonia levels and metabolic alkalosis. Ammonia is an important
toxic to nervous system.
Improvement in mitochondria! disorders.
L-Arginine supplementation leads adenosine production (increase AMP
dephosphorylation) and increase ATP regeneration (via activation of AMPK)
L-Arginine attenuates oxidative stress.

4. Glutathione (antioxidant) increased after L-Arginine intake.
Arginine attenuates skeletal muscle proteolysis.
Nitric Oxid promotes positive bone remodeling (Nitric oxide generated from
endothelial nitric-oxide synthase (eNOS) prevents resorption regulating osteoclast
activity).
Arginine is a source of amidino groups for the formation of Creatine.
4.CAUTIONS.
Arginine hydrochloride may cause metabolic acidosis.
Arginine should be avoided in people with high Arginine levels in the blood.
Avoid with known allergy or sensitivity to Arginine. (rash, itching, or shortness of
breath.)
Arginine may increase the risk of bleeding. Caution is advised in people with
bleeding disorders or those taking drugs that may increase the risk of bleeding.
Arginine may change blood sugar levels. Caution is advised in people with diabetes
or hypoglycemia.
Arginine may cause hyperkalemia (abnormally high levels of blood potassium).
Use caution with phosphodiesterase inhibitors (e.g., sildenafil).
Avoid in doses over 30 grams due to increased risk of toxic effects.
Arginine may cause low blood pressure.
Avoid with nitrates and spironolactone.
5. L-ARGININE IN SUPPLEMENTS PROTOCOLS. RECOMMENDATIONS ON
HANDLING.
Supplement dosage is 400-6,000 milligrams (1,2 or 3 times a day dependant of the
sport and the period training or competition ). Avoid doses over 30 g daily.
In altitude training help athletes to “altitude sickness symptoms”.

5. L-citrulline malate also increases levels of nitric oxide (NO). L-citrulline (is not
subject to pre-systemic elimination) can be converted to L-Arginine and can be
more efficient to increase levels of L-Arginine.
Glutamine also increases plasma concentration of Arginine.
Nitrite and Nitrate plasma levels must be in analysis protocols in order to avoid NO
overproduction when athletes intake several Supplements producers of Nitric
Oxid.
Arginine increase plasma insulin concentration. So you can include in protocols in
order to attenuate decrease in insulin after a large period of training or
competition. Improves glucose tolerance.
In sports with maximum energy requirement from the beginning (football,
basketball…), Arginine help oxygen delivery during the first minutes. The
reduction in oxygen delivery limits the rise in VO2 during several minutes.
Arginine has a short half-life elimination. It is recommended to repeat an
administration in half time of team sports.
In Cycling can be administered dissolved in Hydration liquids.