American Metabolix Havok Review

Havok is a pre-workout from American Metabolix, previously known as American Muscle, which delivers a blend of stimulant and non-stimulant ingredients. Unfortunately, we have our doubts about the levels of certain key ingredients.

American Metabolix Havok



Creatine Magnesium Chelate is Creatine bonded to Magnesium, and was originally invented because of Magnesium’s crucial role in Creatine metabolism. Few studies have been conducted to compare Creatine Magnesium Chelate to other forms of Creatine, but the research that has been conducted indicates it is roughly as effective as Creatine Monohydrate, but not more. A 2004 study, published in “The Journal of Strength & Conditioning Research”, found that 2.5mg of Creatine Magnesium Chelate was equivalent to the same dose of Creatine Monohydrate with regards to increasing 1 rep max in trained men. Although Creatine Magnesium Chelate appears no more effective than Monohydrate in terms of physical performance enhancement, a 2003 study published in “Metabolism” did note that Creatine Magnesium Chelate may result in less water retention. However, more studies are needed for a more direct comparison.


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. The most common form of Creatine is Creatine Monohydrate, which is formed by dehydrating a solution of Creatine, where a single water molecule remains bound to the Creatine powder. Havok contains 2 grams of Creatine in total (from Monohydrate and Magnesium Chelate) which may be effective for maintenance, but likely won’t increase muscle Creatine concentrations to any noticeable degree.


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 offset the mostly negative results of multiple separate studies.


Citrulline is a precursor to the amino acid Arginine, which is a precursor to Nitric Oxide (NO). Citrulline has recently gained recognition in the supplement community for its ability to increase plasma (blood) Arginine levels better than supplemental Arginine itself. 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. 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 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. While Citrulline has demonstrated significant ergogenic effects in animals and humans (in multiple studies), most pre-workout supplements use between 1-2g of Citrulline, the true efficacy of which is still unknown.

Havok contains 1450mg of a combination of Arginine AKG and Citrulline Malate, which means both are under-dosed to say the least.


Beta-Alanine is a precursor to the amino acid Carnosine (formed by combining Histidine and Beta-Alanine). 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 (2+ weeks), can be an extremely effective ergogenic aid 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 in a dose dependent manner. 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.

Havok contains 1750mg of Beta-Alanine and Histidine, meaning there may be an effective dose of Beta-Alanine (at least 1.6g), though we can’t be completely certain.


As mentioned in the Beta-Alanine section, Histidine is required to form Carnosine, and since it is an essential amino acid, it must be acquired through diet (or supplemented). However, while Histidine deficiency can certainly lead to Carnosine deficiency, supplemental doses of Histidine have proved ineffective at boosting muscle Carnosine above baseline, whereas Beta-Alanine is quite effective. So, although the addition of Histidine certainly doesn’t hurt, there no evidence to suggest it conveys any performance benefit beyond that of Beta-Alanine alone.


Tyrosine is a non-essential amino acid which serves as a precursor to the neurotransmitters Dopamine, Norepinephrine, and Epinephrine, the three of which are collectively referred to as ‘catecholamines’. A 1981 study found that subjects who consumed 100mg/kg of Tyrosine experienced a significant increase in urinary catecholamine levels, yet supplemental Tyrosine has failed to produce the performance enhancing effects commonly associated with increased release of catecholamines. This is because Tyrosine does not instantly get converted into noradrenaline, dopamine, or adrenaline. It forms a pool, and when there is a deficit of catecholamines, the pool is drawn from to create more. In other words, Tyrosine may restore levels of dopamine, noradrenaline, and adrenaline when necessary, but does not increase them beyond normal levels. So rather than directly improving physical performance, Tyrosine has demonstrated the ability to improve aspects of cognitive function in the presence of an acute stressor (sleep deprivation, exposure to cold, and possibly exercise).


Caffeine is a well-established ergogenic aid/cognitive enhancer and is the most commonly consumed psychoactive stimulant in the world. Caffeine causes the release of Catecholamines, resulting in increased alertness, focus, and perceived energy. These neurotransmitters tend to be pro-lipolytic, so it is commonly assumed that caffeine is a fat-burner. While the mechanisms of caffeine are certainly pro-fat-burner, the effects tend to fade with prolonged use, rendering caffeine ineffective as a long-term weight loss solution. However, it is a highly effective ergogenic aid and will certainly enhance performance when taken pre-workout. Havok contains 190mg of Caffeine which is enough to promote a sense of alertness and perceived energy in most (non-caffeine tolerant) individuals, especially in combination with the other stimulants in the formula.


Hordenine (chemical name N, N-dimethyltyramine) is chemically related to Tyramine, and likewise, is used in dietary supplements as a fat-burner as well as for increased energy. Hordenine has been shown in animals to augment adrenaline induced muscle contraction while not directly inducing contractions itself, which indicates it works as a monoamine (Adrenaline) reuptake inhibitor (similar to Tyramine). However, we’d like to be very clear that there is very little research published on the use of Hordenine in humans, especially as it relates to physical performance and exercise.


Syneprhine became popular after the FDA banned Ephedra as a dietary supplement for weight loss, because they share a similar mechanism of action. While Synephrine has been touted as a replacement for Ephedra, it is important to understand that it is significantly less potent (which is why it is not banned). However, that’s not to say it is completely useless. A 2011 study, published in the “International Journal of Medicinal Sciences”, found that supplementation of 50mg Syneprhine increased the metabolic rate in human subjects without affecting blood pressure or heart rate. Similarly to Ephedrine, Synephrine is a beta-receptor agonist and an alpha-receptor antagonist, the net effect of which is an increase in lipolysis. Though Syneprhine is significantly less potent than Ephedrine, it is also comparatively much safer and its use is justified by a balance of safety and efficacy.


Contrary to popular belief, Taurine is not a stimulant but rather an an amino acid with anti-oxidant properties. In a 2011 study, Taurine was shown to significantly decrease oxidative stress in skeletal muscle following exercise. Prior to that, a 2004 study showed that Taurine may decrease exercise induced DNA damage, as well as “enhance the capacity of exercise due to its cellular protective properties”. A recent 2013 study noted a 1.7% improvement in 3k-time trial of runners after supplementing with Taurine, but noted that more research would be required to determine the exact mechanism of action.

It’s unfortunate that Taurine has developed a sort of stigma because of its inclusion in energy drinks. While Taurine does not provide “energy” in the way that caffeine does, several studies have shown its effectiveness as an antioxidant with workout-enhancing properties, and while the exact mechanism of action remains unknown, it appears likely that Taurine may improve exercise performance by reducing some of the cellular oxidative damage that generally leads to fatigue. The usual dose of Taurine used for performance enhancement is about 1 gram, though Havok contains a much lower, and probably insignificant, dose.


Ribose is a monosaccharide (simple sugar) which has been alleged to restore ATP post-exercise. However, a 2001 study published in the Journal of Nutrition found that supplementation with 4 grams of Ribose did nothing in the way of restoring post exercise ATP in human subjects. Furthermore, a 2003 study published in the International Journal of Sport Nutrition and Exercise Metabolism found that supplementation with 10 grams/day had no effect on anaerobic exercise capacity in healthy adult males. A 2004 study concluded that the availability of ribose does appear to be a rate-limiting factor the re-synthesis of ATP post-exercise, and that 200mg/kg Ribose was an effective dose for restoring ATP levels post-exercise. While we can’t be certain how much D-Ribose is present in the Havok blend, we can be certain that it is far less than what has demonstrated efficacy in the above mentioned study, which means it is likely a pointless addition to the formula.


Rauwolscine (also known as alpha-yohimbine) is a ‘stereoisomer’ of Yohimbine, meaning it is chemically similar in structure and function. Like Yohimbine, Rauwolscine is a beta-adrenergic agonist which causes a release of noradrenaline. Aside from inducing lipolysis, Rauwolscine may also amplify the effects of the other CNS stimulants present in the Havok formula, contributing to increased alertness/focus/perceived energy.


Havok is certainly going for an all-in-one approach by including several standard pre-workout ingredients (Creatine, Citrulline, Beta-Alanine, etc.) as well as several stimulants. However, most of those standard pre-workout ingredients are under-dosed, some (such as Citrulline) quite significantly. With the exception of Niacin (unnecessary), the stimulant blend is actually well constructed and may certainly provide the increased alertness and energy that so many pre-workout users are seeking. However, at about $2 a dose, Havok is extremely over-priced, given a relative reconstruction cost of less than a dollar. Ultimately, we cannot recommend Havok when there are so many more all-in-one type pre-workouts which contains effective doses of key ingredients.

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