Despite sounding like a second-rate member of the X-men, Muscle Factor X is actually a second-rate muscle-building supplement. This is a classic example of hypermasculine branding in the supplement market and comes across as hilarious more than hyperbolic.
The supplement is sold based on the fact that it only contains natural ingredients, in contrast to the medical-sounding name. We’re not sure what brought this mixture of messages about, but the marketing and presentation of this product is the copywriting equivalent of a Michael Bay movie.
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We’re going to look at whether this is actually going to help you grow muscle and how the individual ingredients of this supplement affect your health, strength, physique, and performance. We’re not sure that they’ve stumbled onto a muscle building X-factor, but we’ll see what the science has to say.
What is Muscle Factor X?
Cutting through the hyperbole, Muscle Factor X is all about nitrogen levels. Nitrogen levels in the muscles are important for recovery between workouts and muscle protein synthesis: they modulate your ability to build muscle tissue and improve strength.
Arginine is a common way of trying to improve nitrogen balance and return to healthy levels after exercise when these crucial compounds are depleted. Serum arginine (the amount in your blood) has been shown to be an important predictor of recovery and growth, but oral supplementation is unreliable.
Muscle Factor X provides 3 different forms of arginine, each providing 1/3 of the total load. This includes two forms of common arginine (Monohydrate and L-Arginine), as well as L-Arginine Alpha-Ketoglutarate and L-Citrulline. The first 3 of these are basically just arginine in different forms, aiming to get past absorption problems by throwing more arginine at your body.
Citrulline is a pre-arginine compound that is absorbed and converted to arginine in the body. This has the same goal as regular arginine supplementation but is likely to have a greater effect on the arginine in your bloodstream . This makes it a natural addition to what is, fundamentally, an arginine supplement.
Does it Work?
The problems with absorption don’t seem to be the largest block to the effectiveness of this supplement. Rather, the role of arginine in the development of muscle is the real question here.
Arginine can be an important mediator for recovery and plays an important role in the development of muscle and strength. The degree to which arginine boosts muscle growth is both unreliable and significantly less than marketing might suggest .
What you’re likely to experience is an improvement in your overall endurance and time-to-fatigue in the gym . This increases your ability to increase training volume which, when paired with proper nutrition and rest, will induce greater muscular improvements.
Diabetics and Health
Arginine is also a key player in the metabolism of glucose and has interesting effects on diabetics. Research suggests that arginine has positive effects on glucose metabolism and exercise-induced metabolic improvements among diabetics.
This suggests one of two things:
- Arginine will improve the health and wellbeing of those struggling with diabetes regardless of other environmental factors, or
- Arginine boosts the positive effects of exercise and activity on the insulin sensitivity of those with diabetes and pre-diabetic symptoms 
In either situation, arginine is a great way of adapting to a healthier and more well-balanced lifestyle for those with Type-2 diabetes. This means an increase in the speed of transition and the overall healthfulness of positive lifestyle change.
Overview and Applications
The first problem we run into is that the scientific literature indicates that arginine won’t reliably produce extra muscle-building effects . Positive benefits tend to be below the threshold for statistical significance, so we can’t expect any considerable results from supplementation.
It’s also important to watch out for resting levels of nitric oxide. A course of supplementations to improve NO2 production can improve endurance, which makes it a solid choice for endurance athletes, but consistently elevated serum NO2 levels can produce negative health effects and contribute to overall toxicity .
With the concentration of NO2 sources in this product and the suggested usage, it is important that your supplementation is closely-matched to your exercise volume, or you might experience some of the negative effects of chronic NO2 toxicity.
Practical Stuff and Concerns
The first thing that screams out at us is the sheer expense of this product. At the better part of $80 per bottle, which provides around 4 weeks of supplements, this supplement is more than twice as expensive as common PEDs!
With the limited effects you’re going to see, we strongly recommend looking at market alternatives: citrulline and arginine supplements abound and with much more reasonable price points. We don’t take issue with the effectiveness of this product but there are objectively better value supplements on the market.
The Upshot: What do we Think?
The first thing to note is that this product is not going to be as effective as their marketing suggests. This is perhaps the unspoken law of supplement marketing, but it's always important to temper your expectations if you’re keen to purchase a supplement. Muscle Factor X won’t live up to its own hype, despite some positive effects.
The overall effectiveness of this product is going to be relatively unimpressive: small boosts in endurance accompanied with an increased work capacity. Boosts in endurance are best in combination with other compounds like beta-alanine but, overall, it’s not going to be appreciable.
Competitors on the market provide equally-effective Arginine and Citrulline supplements with a much more cost-effective price tag. In this sense, there’s nothing wrong with Muscle Factor X but with a market so heavily saturated and a high cost, we can’t recommend this particular supplement.
Editor's Tip: After reading the conclusion about Muscle Factor X, please check out PhentaSlim to see why it is our #1 recommendation.
The effectiveness of dietary supplements always needs to be weighed up against the cost and the alternatives. When we apply these lenses to the effectiveness and benefits of Muscle Factor X, it is obvious that it is a poor choice.
As with many other supplements, the worst thing that can be said of Muscle Factor X is that it is profoundly underwhelming. The benefits are limited to improvements in at-risk populations for diabetes and mild endurance boosts.
When we look at Muscle Factor X we’re unimpressed by the benefits and overwhelmed by the costs. Beyond this, the supplement is ‘middle of the road’.
Steven has researched over 500 weight-loss programs, pills, shakes and diet plans. He has also worked with nutritionists specializing in weight loss while coaching people on how to transform their physiques and live healthy lives.