Met-Rx Nuclear X Review

Nuclear X

Nuclear X is a pre-workout by MET-Rx which features a variety of pretty standard pre-workout ingredients, the only stimulant being Caffeine…


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Nuclear X is a pre-workout by MET-Rx which features a variety of pretty standard pre-workout ingredients, the only stimulant being Caffeine…[Skip to the Bottom Line]


Beta Alanine is a non-essential amino acid that, along with Histidine, serves as a precursor to the amino acid Carnosine. Carnosine acts a lactic acid buffer, effectively delaying fatigue in the working muscle. Beta Alanine takes time to accumulate, but if taken over a sustained period of time (a few weeks), can be an extremely effective performance enhancing supplement with a strong safety profile.

One study in particular that measured the carnosine levels of sprinters found that individuals with higher muscular Carnosine levels exhibited higher power output in the latter half of a 30m sprint (because they had less lactic acid build-up). Multiple studies have confirmed that Beta Alanine supplementation increases muscular Carnosine, which improves physical performance.

In particular, a 2012 study published in “Amino Acids” found that subjects who consumed 1.6 or 3.2 grams of Beta Alanine daily experienced significant increases in muscle carnosine in as little as two weeks, with the higher dose achieving a higher concentration of Carnosine. Nuclear X contains a hefty 2.4grams of Beta-Alanine, more than most pre-workouts and definitely a highly effective dose.


Arginine is a non-essential amino acid that acts as a precursor to Nitric Oxide. Supplement manufactures claim that, because Arginine is a precursor to Nitric Oxide, supplemental Arginine may boost Nitric Oxide levels, resulting in vasodilation. However, recent studies have found that Arginine isn’t all it’s cracked up to be.

The human body is complex and, unfortunately for supplement companies, ingesting a precursor to a substance doesn’t necessarily increase the levels of that substance. A 2012 study, published in “Nutrition and Metabolism”, found that acute (one-time) L-Arginine supplementation with 6 grams did not increase plasma (blood) levels of Nitric Oxide in people with normal Asymmetric Dimethylarginine levels. Asymmetric Dimethylarginine is a compound that is chemically related to Arginine and directly interferes with the production of Nitric Oxide.

Furthermore, recent studies have questioned whether Arginine may in fact be counter-productive during exercise.

A 2011, placebo controlled study, found that subjects performed worse after receiving 3700mg of Arginine Alpha-Ketoglutarate prior to resistance training. Due to the size of this study, it cannot be considered conclusive, but it certainly should warrant further studies.

While most studies have failed to prove that L-Arginine supplementation increases strength, a 2012 double-blind placebo controlled study, found that supplementation with 6 grams of L-Arginine increased muscle blood volume post-workout, but did not increase intra-workout strength. While this may be disappointing for those looking to increase strength through supplementation, Arginine’s real benefits may lie in post-workout recovery, rather than intra-workout performance.

More blood in the muscle’s after a workout means more nutrients to the muscle cells. However, this one study does not offset the mostly negative results of multiple separate studies. Nuclear X contains 1.5 grams of Arginine in the form of Arginine AKG, which unfortunately has not shown much promise in terms of performance enhancement.


Citrulline is a precursor to the amino acid Arginine, which is a precursor to Nitric Oxide (NO). A 2009 study, published in the “Journal of Free Radical Research”, found that 6 grams of Citrulline Malate given to male cyclists before a race increased “plasma Arginine availability for NO synthesis and PMNs priming for oxidative burst without oxidative damage”.

You may be wondering: How can Citrulline be more effective at increasing Arginine than Arginine itself? The problem with supplemental Arginine is that it is metabolized in the intestines and liver into other substances such as Ornithine and Urea. The intestines and liver contain relatively high levels of Arginase, the enzyme that converts Arginine to Ornithine and Urea. As a result, very little goes on to be involved with the synthesis of NO because it is being diverted for other purposes. Citrulline, on the other hand, is able to bypass the liver and is metabolized into Arginine elsewhere, where not as much Arginase is present. Thus, more of the Arginine is able to convert into NO.

A 2002 study, published in the “British Journal of Sports Medicine” found that Citrulline Mallate supplementation (6g/day for 15 days) significantly increased ATP production during exercise in healthy adult males. A 2011 study, the subjects of which were rats, found that supplemental Citrulline increased muscular contraction efficiency (less ATP was required for the same amount of power), in-line with the findings of the above-mentioned human study. Nuclear X contains 1 gram of Citrulline DL-Malate at a 1:1 ratio which unfortunately means the actual amount of Citrulline is only 500mg, far less than what has demonstrated clear efficacy in the above mentioned studies.
Creatine has the ability to rapidly produce ATP (cellular energy) to support cellular function (as in exercise). It has been studied more extensively than any other performance enhancing supplement, and has consistently been demonstrated to increase power output as well as muscle size, with maximum benefit achieved at around 8 weeks of consistent supplementation. During high intensity exercise, Creatine is used for energy which tends to spare the glycogen that would normally be used. Since lactic acid is a by-product created when glucose is burned for energy, Creatine may also indirectly reduce lactic acid build-up which poses a secondary mechanism by which Creatine can potentially enhance performance.

It is generally recommended to consume 5 grams per day but lower doses (3 grams) can still be effective if consumed over a longer period of time. 2 grams daily has been demonstrated to maintain Creatine levels (but not increase them) in athletes. Creatine comes in various forms, the most common of which is Creatine Monohydrate, which is formed by dehydrating a solution of Creatine, where a single water molecule remains bound to the Creatine powder. However, Nuclear X contains another form of Creatine known as Creatine Hydrochloride, which is made by adding hydrochloric acid to a solution of creatine, forming a salt. Creatine HCL is more water soluble than Monohydrate, but in the stomach it is reduced to the same basic Creatine molecule and has never been shown to be more effective, just easier on the stomach.

Nuclear X contains only 1 gram of Creatine, far less than what has been demonstrated to increase muscular Creatine levels, so we’d recommend anyone seeking to gain the full performance benefits of Creatine take additional Creatine (3-4 grams).


Agmatine remains very under-researched, despite possessing a variety of health/performance implications. Recently, Agmatine has become quite pervasive in pre-workout supplements because of its alleged ability to regulate Nitric Oxide Synthase (NOS), an enzyme that catalyzes the production of NO from Arginine, and either elevate or reduce its presence, depending on the type of NOS. NOS is a widely misunderstood enzyme, mostly due to supplement companies not properly explaining its function and how that function relates to physical performance. It is largely thought that NOS is the enzyme that “breaks down” NO, when it is actually the enzyme that catalyzes the production of NO from Arginine in the first place.

Nitric Oxide generally has a positive connotation in the bodybuilding/athletic community because it is associated with vasodilation, which clearly has performance/health benefits. However, this beneficial effect of NO only pertains to NO in the blood vessels. Elsewhere in the body (like the brain) NO can inflict damage and actually be quite harmful. So ideally, what we really are after is a way to reduce NO in the areas of the body where it can cause harm, while increasing it in blood vessels where it can beneficially influence physical performance.

It’s important to understand that there are several types of NOS, all which are required for the production of NO. Inducible NOS (iNOS) and Neuronal NOS (nNOS) are considered harmful because they elevate NO in immune cells (causing inflammation) and the brain (causing neuronal damage), while Endothelial NOS (eNOS) is considered beneficial as this is the kind which increases Nitric Oxide in the blood vessels, resulting in vasodilation. Agmatine has been demonstrated to up-regulate eNOS (the “good” NOS) while inhibiting the other NOS enzymes (the “bad” NOS). However, as mentioned above, Agmatine remains under-researched because it is a relatively new entrant in the supplement industry. Currently, most of the research has been done in vitro, with absolutely no studies regarding the potential physical performance benefits of Agmatine in humans. Because of the lack of human studies, no optimal dose has been established for Agmatine, though average doses in pre-workout formulas are 500-1000mg.


Caffeine is the most widely consumed psychoactive substance in the world, and is a well-established ergogenic aid. Caffeine consumption causes an increase in Catecholamines (Adrenaline, Noradrenaline, and Dopamine), which tend to increase focus, concentration, and perceived energy while simultaneously promoting fat oxidation. However, this increase in fat-oxidation tends to fade with prolonged use, so it does not appear as though caffeine is a long-term effective fat burner. While caffeine’s weight loss potential is negligible, it increases focus and perceived energy in most people, which generally leads to more intense workouts. Nuclear X contains 200mg of Caffeine which is enough to provide the average non-caffeine user with a noticeable increase in alertness and perceived energy. Those who frequently consume caffeine may not notice as much of a boost at this dose.


Nuclear X contains a highly effective dose of Beta-Alanine, but the levels of the rest of the ingredients are less than optimal. The only stimulant it contains is caffeine making it an option for those who prefer to avoid the less-researched stimulants found in so many other pre-workouts these days. However, to truly convey the benefits of the other ingredients (except Beta-Alanine), multiple servings would have to be consumed. At a price of about 90 cents per serving, Nuclear X costs about the same as it’s estimated re-construction cost.

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