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Acute L-arginine supplementation reduces the O2 cost of moderate-intensity exercise and enhances high-intensity exercise tolerance

Stephen J. Bailey,1 Paul G. Winyard,2 Anni Vanhatalo,3 Jamie R. Blackwell,1 Fred J. DiMenna,1 Daryl Paul Wilkerson,3 and Andrew M. Jones1,*

1Exeter University ; 2Peninsula College of Medical School ; 3University of Exeter

Submitted 10 May 2010 ; revised 30 July 2010 ; accepted in final form 17 August 2010

It has recently been reported that dietary nitrate supplementation which increases plasma nitrite concentration, a biomarker of nitric oxide (NO) availability, improves exercise efficiency and exercise tolerance in healthy humans. We hypothesised that dietary supplementation with L-arginine, the substrate for nitric oxide synthase (NOS), would elicit similar responses. In a double-blind, crossover study, nine healthy males (aged 19-38 years) consumed a 500 mL beverage containing 6 g of L-arginine (ARG) or a placebo beverage (PLA), and completed a series of 'step' moderate-intensity and severe-intensity exercise bouts 1 h post-ingestion. Plasma [nitrite] was significantly greater following L-arginine consumption compared to placebo (ARG: 331 ± 198 vs. PLA: 159 ± 102 nM; P<0.05) and systolic blood pressure was significantly reduced (ARG: 123 ± 3 vs. PLA: 131 ± 5 mmHg; P<0.01). The steady-state VO2 during moderate-intensity exercise was reduced by 7% in the ARG condition (ARG: 1.48 ± 0.12 vs. PLA: 1.59 ± 0.14 L•min-1; P<0.05). During severe-intensity exercise, the VO2 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. In conclusion, similar to the effects of increased dietary nitrate intake, elevating NO bioavailability through dietary L-arginine supplementation reduced the O2 cost of moderate-intensity exercise and blunted the VO2 slow component and extended the time-to-exhaustion during severe-intensity exercise.

Source: http://jap.physiology.org/cgi/content/abstract/japplphysiol.00503.2010v1

Comments:
In this study, healthy individuals are given 6 grams of arginine to evaluate their exercise endurance. Arginine is a non-essential amino acid, which means that the required amount can be obtained from food. Arginine is also sometimes referred to as ‘conditionally essential,’ as it may become necessary under periods of growth and for recovery after injury. Arginine is mainly known as the precursor of nitric oxide (NO), which in turn relaxes blood vessels (vasodilator effect) thereby reducing blood pressure levels. NO may also help to increase exercise efficiency and wound healing. Arginine reduces the accumulation of ammonia and plasma lactate, byproducts of muscle metabolism, thereby increasing exercise tolerance. The human body can only manufacture nitric oxide from arginine. Therefore, arginine is rapidly becoming a popular supplement in sports nutrition.

In addition to nitric oxide, Human Growth Hormone (HGH) has also gained tremendous popularity as a sports performance enhancing and anti-aging compound. However, growth hormone cannot be taken orally as it is easily broken down in the digestive tract. Arginine is a very potent stimulator of human growth hormone and is often used as a substitute for injectable HGH supplementation. The ability of arginine to induce HGH is highly dependent on a person’s age. People in their 20s seem to have a massive growth hormone release after taking arginine, yet, when they reach 40-50 years of age, the effect greatly diminishes. However, it is very important to note that growth hormone releasers like arginine should not be used by young people until five years after they have completed their long bone growth and that such administration requires very close monitoring. Moreover, unnatural increase in growth hormone has also been related to causing or promoting cancer. HGH stimulates the liver to produce excessive insulin-like growth factor (IGF-1). Elevated IGF-1 levels are strongly associated with colon, prostate and breast cancer.

Arginine also induces pancreatic secretion of the hormone glucagon. Glucagon effectively increases blood sugar levels. Therefore, the administration of high doses of arginine requires frequent blood sugar monitoring in diabetic individuals.

Every nutrient requires certain other synergistic nutrients for proper functioning. Very high doses of any single nutrient do not provide the desired benefits and, at times, mega doses of a single nutrient may potentiate the deficiency of other dependant nutrients. For example, the amino acid proline is closely associated with effective arginine metabolism and its utilization at cellular level. Similarly, human growth factor release from arginine is highly dependent upon the concomitant supplementation of choline and vitamin B5. There is also some evidence that an arginine-lysine combination causes more effective release of growth hormone at lower doses.

Dr. Rath has incorporated this innovative concept, which is termed nutrient synergy, in his research. According to this concept, it is not the intake of any one single nutrient that ensures full health, but the intake of a complete spectrum of various different micronutrients, such as vitamins, minerals, amino acids and trace elements. The clinical effectiveness of this approach has been confirmed not only in many of our own studies, but also through other independent research. Dr. Rath's Cellular Health research focuses on nutrient synergy as the most effective approach to optimizing cellular metabolism and restoring its balance, and has repeatedly shown that this approach is more effective than using individual nutrients, or their random combination. You can find more information about Dr. Rath's research at: www.drrathresearch.org