Citrulline is the most effective ingredient in a great preworkout supplement.
Yeah, I said it.
If you are unsure what citrulline is – or what it actually does – then today’s article will give you a quick walkthrough guide.
What Is Citrulline?
Commonly found in watermelon, citrulline is an amino acid.
When found in supplements, you’ll usually hear it referred to as citrulline malate. This is citrulline with a malic acid molecule attached to it (malate).
Occasionally, you’ll hear supplement companies attaching these molecules in a different ratio, such as two citrulline molecules to one malic acid molecule (a 2:1 ratio, as seen in Pre Jym).
Here are the main selling points of using citrulline before workouts:
- Increased muscular endurance
- Increased pump
- Increased levels of growth hormone
Pretty good, right?
This is why citrulline features prominently in my article about how to make your own preworkout.
If you are wondering how a simple substance like this can enhance your ability to train harder for longer, it doesn’t give you super powers.
Instead, it’s all about lactic acid build-up.
Don’t get this confused with beta-alanine, though.
Beta-alanine possesses the ability to temporarily buffer the onset of lactic acid. Citrulline, on the other hand, widens the blood vessels (more on this later) and enables your body to shuttle away lactic acid which has built up.
By enhancing your body’s ability to clear away the lactic acid which builds up inside your muscles (a.k.a. “the burn”) when you are training through a motherfucker of a set, you unlock the ability to train at peak levels for longer than usual.
The inclusion of the malic acid molecule will also boost your body’s production of ATP, which will enable you to recover slightly faster between sets.
A fabulous 2010 study published in the Journal of Strength and Conditioning Research looked at the effects of citrulline before a heavy chest workout. Providing one group of subjects with a preworkout serving of citrulline and another group with a placebo, the researchers waited to see whether the citrulline would result in greater muscular endurance and recovery.
They found that from the third set of the workout, the group who used citrulline were able to perform an average of 1 more repetition on every single set. (1)
You see, citrulline has the unique abilities of being able to increase your capacity for training through “the burn” and boost your recovery speeds between workouts.
If you are training as hard as Rocky in a Russian barn, these are great assets.
Citrulline Vs Arginine
Now that I’ve established some of the “jobs” citrulline will perform, if you know your supplements you are probably already thinking it sounds an awful lot like arginine.
Just like citrulline malate, arginine is another substance which is very commonly found in preworkout supplements and you are correct in noticing that it performs many of the same tasks.
Supplementing with arginine allows your body to increase nitric oxide levels, allowing your blood cells to widen and deliver more nutrients during training. (2)
And more nutrients delivered to your working muscles = greater training endurance.
It’s kinda like when Joey wore his Thanksgiving pants.
That’s the basis every N.O. supplement on the market has been based upon since their introduction to the supplement world more than a decade ago.
Furthermore, due to the fact that our blood cells have widened to allow for greater delivery of nutrients, they are also receiving a greater blood flow than usual. As blood is 50% water, this is why you get a great pump.
But here’s the thing – arginine js not absorbed very well by the body.
One useful study found that when participants used citrulline instead of arginine, they had higher levels of arginine in their blood when they used citrulline. Another study, this time published in the British Journal of Pharmacology, discovered that citrulline is 50% more potent than arginine supplementation for raising blood levels of arginine. (3, 4)
This means that using citrulline malate is actually a superior way of getting the full benefits of arginine than using arginine directly!
Yup, once inside the body, arginine lasts about as long as a child abuser in gen pop.
This is because most of our arginine serving will be destroyed in the liver and intestines, meaning we would need a rather large dose to achieve the kind of training results arginine is capable of. In fact, one study even suggested that as little as 1% of your typical arginine dose makes it to the muscle cells. (5)
Citrulline, on the other hand, bypasses the liver and intestines, heading straight to work.
A study from Spanish researchers found that around 80% of your citrulline dose actually makes it to your kidneys and gets converted to arginine. (6)
So it’s the fact that arginine gets battered upon entering the body, while citrulline simply sets about it’s job, that makes it a superior option for gaining the nitric oxide boosting benefits which are waiting to be had.
It will also boost growth hormone levels, as mentioned in the droplist above, but I’m not a fan of supplements which boost GH levels. This is because it’s an overhyped benefit. Temporarily boosting your levels of growth hormone while training simply does not give you any real edge when it comes to building more lean muscle. (7)
How Much Citrulline Should You Use?
This is where most supplement companies try to catch you out.
Manufacturers want to keep costs down, and have a number of bad habits they continually use regarding citrulline.
A lot of manufacturers will either hide their dosages behind a proprietary blend (meaning you know citrulline malate is contained within the product, but have no idea how much), use a combination of citrulline malate and arginine (we’ve already shown why this isn’t necessary) or use the standard form of citrulline (l-citrulline, not citrulline malate).
The final bad habit is to simply underdose the product and presume you won’t even notice.
So, the next time you are looking at a preworkout supplement try to find one which will provide you with 6-8 grams of citrulline malate.
This will be significant enough to give you the full potential training benefit on offer.
Should You Start Using Citrulline?
Do you perform endurance based training or a heavy weights-based routine?
Citrulline malate would be a great addition to your diet, whether as part of a preworkout or via a standalone citrulline product.
It’s a substance that most of my clients have used for the last 10 years, and one of the few preworkout ingredients to be genuinely as useful as it claims to be.
When I’m buying citrulline as a standalone (such as when I’m making my own pre) this is the one I buy.
- Pérez-Guisado, J., et al. Citrulline malate enhances athletic anaerobic performance and relieves muscle soreness. J Strength Cond Res. 2010 May;24(5):1215-22. doi: 10.1519/JSC.0b013e3181cb28e0.
- Alvares, T. S., et al. Acute l-arginine supplementation increases muscle blood volume but not strength performance. Appl Physiol Nutr Metab. 2012 Feb;37(1):115-26.
- Kuhn, K. P., et al. Oral citrulline effectively elevates plasma arginine levels for 24 hours in normal volunteers. Circulation 2002; 106: II1–766S.
- Schwedhelm, E., et al. Pharmacokinetic and pharmacodynamic properties of oral L-citrulline and L-arginine: impact on nitric oxide metabolism. British Journal of Clinical Pharmacology, 65(1):51-9, 2008.
- Castillo, L., et al. Splanchnic metabolism of dietary arginine in relation to nitric oxide synthesis in normal adult man. Proc Natl Acad Sci USA 1993; 90: 193–7.
- Sureda, A., et al. Arginine and citrulline supplementation in sports and exercise: ergogenic nutrients? Med Sport Sci. 2012;59:18-28. doi: 10.1159/000341937. Epub 2012 Oct 15.
- West, D. W., et al. Associations of exercise-induced hormone profiles and gains in strength and hypertrophy in a large cohort after weight training. Eur J Appl Physiol. 2012 Jul;112(7):2693-702. doi: 10.1007/s00421-011-2246-z. Epub 2011 Nov 22.