ergogenic aid for increase sports performance seems to have potential () L-Arginine as a Potential Ergogenic Aidin Healthy Subjects. L-arginine as a potential ergogenic aid in healthy subjects. Sports Medicine, 41(3 ), doi/ Bahra, M., Kapil, V. Dietary nitrates and L-Arginine have been increasingly recognized to play a promising Recently, nitric oxide (NO) has emerged as a promising ergogenic aid by .. factor for exercise tolerance in healthy subjects, suggesting the potential of.
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Nitric Oxide NO is an endogenous free radical and a potent vasodilator in the human body. While it has many clinical applications, interest in NO use as a potential ergogenic aid has increased greatly in recent years. There are now many different types of NO-producing supplements, split into three major categories: Recent literature has yielded mixed results zid all three. Arginine-based supplements work in some suubjects, but have several recurring limitations that question the validity of their conclusions.
There is currently no conclusive or decisive evidence to support the claims made regarding arginine or citrulline-based supplements.
Nitric Oxide/Arginine: Is Cardiovascular Modulation Effects in Athletes Supplementation?
Nitrate-based supplements taken 2. The amount of nitrate that needs to be consumed to obtain ergogenic effects can be obtained through a meal of g of nitrate-rich vegetables such as beetroot, spinach, and lettuce. Considering the unstable nature of nitric oxide, there is also a lack of studies observing the magnitude of protein damage over chronic supplementation. There is also a lack of studies that observed elderly and female populations.
Future studies should investigate the effects of chronic supplementation on 3NT levels—a marker of protein damage. Vasodilation is the process by which blood vessels increase in diameter, allowing for an increase in blood flow. However, NO is an unstable free radical, meaning that it is a compound that has potential to cause cellular damage if it is in high concentrations. This is avoided because NO is stored in the body as its more stable forms: NO can be safely produced via oral bacterial enzymes that can convert NO 3 to NO 2which can then be converted to NO by a number of other enzymes in the body Lundberg et al.
The primary method of increasing NO and inducing vasodilation, however, is through the activation of Nitric Oxide Synthases NOS located in endothelial cells. With the help of oxygen, NOS convert arginine Arga conditionally essential amino acid i. NO then diffuses into smooth muscle cells causing changes that lead to smooth muscle vasodilation Lundberg et al. Historically, NO has been widely used in clinical settings because of its vasodilatory effects.
Interest and research in the field of NO-producing supplementation for sport performance has grown immensely in the past 30 years. Indeed, studies show that people with impaired NO synthesis have poor exercise tolerance Lauer et al. The three major forms of NO-producing supplementation include arginine, citrulline, and NO 3 – based supplementation.
Arginine and citrulline-based supplements work by increasing the amount of substrate arginine for NOS, leading to an increase in NO production. Citrulline Cit is a non-standard amino acid that can be converted to arginine in the body with the help of several enzymes Toda, This paper will explore whether or not these common forms of NO supplementation work, through which mechanisms they might act, and under what conditions.
We reviewed 20 studies that used Arg-based supplements and found mixed results. Out of 20 studies, nine claimed the supplement worked while 11 claimed it did not Appendix, Table 1. However, when we examined these studies, we came across several recurring limitations that must be addressed.
First, many of the Arg supplements reviewed were mixed with other compounds, most of which had their own ergogenic effects. For example, Chen et al. However, the supplement was mixed with several other compounds including citrulline, vitamin E, and alpha lipoic acid; therefore, the authors could not conclude that the increase in anaerobic threshold was solely due to L-arg.
We found that 12 of the 20 Arg studies we reviewed included some form of mixed supplement Appendix, Table 1.
Seven of those 12 studies concluded that Arg supplementation worked as an ergogenic aid. The mixed supplementation casts doubt on the validity of these conclusions. The second major limitation was that only five out of the 20 studies we reviewed measured NO metabolite levels NOX, referring to NO 3 or NO 2 in the bodyand only one of those five reported a significant difference in NOX levels Bailey et al.
This makes it difficult to know if the results of these studies can be attributed to NO supplementation. The third limitation is that arginine is iin in several other metabolic pathways. This means it may not always lead to an increase in NO production. This was well illustrated in a prior study conducted by Fricke et al. The authors found no increase in maximum grip force, or peak jump force, but did find a significant increase in maximum power in relation to body mass measured as peak jump force divided by body weight.
They concluded that the supplement may have increased maximum force and prevented muscle force decline in postmenopausal women. However, while these authors concluded that Arg supplements can have a positive benefit, they also note NO was likely not the cause of the observed result and stated that increased Arg may not necessarily lead to an increase in NO synthesis. Arg is known to actively participate in the synthesis of creatine Buford et al. It is difficult to ai the ergogenic q of Arg-based supplementation to arginine itself.
Arg is active in many other pathways and may not always stimulate NO production. Arginase activity seems to increase with exercise, which suggests additional arginine will not be converted to NO Sureda et al.
Like Arg-based supplements, Cit-based supplements are also Ergigenic dependent; however, unlike Arg, Cit is not a substrate for arginase enzymes. We came across only one Cit-based study that did not use a mixed supplement.
Subjects were given an oral L-Cit supplement, and then completed an incremental test to exhaustion on a treadmill Hickner et al. In light of the findings outlined above and the reported side effects of Arg and Cit-based supplementation e. We reviewed 27 studies that used one of these forms of NO 3 -based supplementation.
Appendix, Table 2 summarizes each study and Table 3 provides an overall summary of the findings. Like the Arg-based studies, the NO 3 studies produced varying results, though 22 out of 27 showed a performance benefit. For example, Wilkerson et al. Studies also show that the optimal time to l-argimine NO 3 supplements is 2. Unlike the Arg-based studies, all NO 3 studies reported an increase in NOX levels, regardless of whether or not there potentiap a positive performance effect reported.
This suggests that the subjects in these studies had a lower response to NO supplementation compared to those in other studies.
Further investigation revealed that the subjects of these studies had one trait in common: VO2max is a measure that reflects maximal oxygen uptake. A higher VO2max means that more oxygen can be used during exercise.
With all other variables being controlled, these athletes did not show any performance enhancement through NO supplementation. This is a previously unreported finding, and we believe this is the single-most-important factor in determining whether or not NO 3 supplementation will have an ergogenic effect.
Illustrating this point, a recent study investigated the effect of 6. This is despite having similar experimental protocols as two other studies that reported a benefit from NO 3 supplementation Lansley et al. Unlike the mixed supplementation used in Arg-based supplementation studies, NO 3 was shown to be the active ingredient in the three different forms of NO 3 supplementation used in the NO 3 studies that we reviewed.
Another recent study was able to isolate the effects of BRJ supplementation to its high NO 3 content and not any other substance Lansley et al.
Together, these studies show that NO 3 is the active ingredient in pharmaceutical and dietary nitrate supplementation. Performance benefits were not consistent across the different nitrate studies reviewed i. We believe the reason for this is the vastly different methodology used in each study. It is also important to note that a few studies had experimented with NO 3 supplements that had been mixed with other compounds.
We did not review these extensively because, like the mixed arginine supplements, it is difficult to attribute mixed supplement effects to NO alone. These mixed compounds include 2-ethyl, GPLC a carnitine-based supplementand store-bought NO 3 supplements that were reported to be mixed with over 30 other compounds Bloomer et al.
There have been several controversies surrounding the use of NO 3 supplements. Of minor concern is that subjects who supplemented with BRJ also reported minor side effects such as Beeturia and red stools Bailey et al.
The most significant controversy is concerned with the use of pharmaceutical NO 3. Due to health and ethical concerns, human supplementation with pharmaceutical NO 3 was not allowed in the United Kingdom Jones et al. Some researchers have claimed, however, that even at low levels NO 3 could be dangerous, and they have warned against its uncontrolled use e. This study concluded that acute supplementation of NaNO 3 was safe for humans if consumed alongside dietary nitrate.
Therefore, the concerns surrounding NO 3 use as an ergogenic may not be applicable in all situations. NO supplements are increasingly being used by recreational athletes as an ergogenic aid, but little is currently known about the nature of these supplements.
After reviewing recent literature, several conclusions and inferences may be made. Arg and Cit supplements that use endogenous NOS to convert Arg to NO have yielded inconsistent results and there are no consistent data from which to make any reliable conclusions. NO 3 -based supplements show the most promise. There is a strong correlation between the change in plasma NO 2 levels and a change in performance.
These supplements have been shown to work across a large range of aerobic exercise modalities. While all NO 3 supplements are shown to exert their effect by increasing NO, this increase is dependent on the training status of the individual.
Highly trained athletes have the lowest-percent potwntial post-ingestion and are not likely to gain any performance benefit from the additional Healrhy 3.
Despite such fears, NaNO 3 supplements, if taken ergogejic with dietary nitrate, do not cause any significant protein damage over an acute dosage period. Chronic exercise has also been shown to increase NOS expression in dogs Sessa et al. It is possible that chronic exercise training over a lifetime may increase NOS expression in human subjects to the poyential where NO 3 supplementation is no longer effective, which may be the case with highly trained athletes.
This subiects potential implications for elderly populations, who are known to have decreased levels of NO production Goubareva et al.
L-Arginine as a potential ergogenic aid in healthy subjects.
In addition, excessive NO production is dangerous because of its capacity for protein damage. Therefore, future studies should examine the effects of chronic exercise on NOS expression, the effects of NO 3 supplementation in elderly populations, and 3NT levels over chronic supplementation periods.
After reviewing all the pertinent literature, the claim can be made that NO 3 supplements can help to improve aerobic exercise tolerance and performance in young, moderately trained men and are not suitable for highly trained endurance athletes.
Arg and Cit-based supplements are not recommended.
Rather than buying a supplement, however, it is recommended that individuals interested in NO 3 supplementation should consume about g worth of NO 3 -rich vegetables 2. One would receive the same amount of NO 3 as the subjects in most of the studies reviewed and save a considerable amount of money. Influence of chronic supplementation of arginine aspartate in endurance athletes on performance and substrate metabolism.
International Journal of Sports Medicine26 5 ,