Last updated on May 9th, 2018
Citrulline, or L-Citrulline, is one of a few ingredients included in pre-workout supplements to enhance the muscle pump effect from resistance weight training.
Getting “pumped” or “swole” when lifting weights has been proven to have both short-term and long-term benefits to muscle growth and strength.
High volume hypertrophic weightlifting sets are the cornerstone of bodybuilding, and any ingredient which can widen the blood vessels a little, allowing more blood, oxygen and nutrients to the muscles is a winner for the professional and amateur alike.
Nitric Oxide (NO) is the key compound in achieving a good muscle pump. It works by relaxing the smooth muscle that lines the walls of blood vessels, thus dilating them for increased blood flow.
The mechanical action of contracting and extending muscles under load together with the increase in blood flow serves to trap the blood in the muscle tissue. This is what gives the pumped up effect.
Citrulline for Muscle Building and Performance Enhancement
Anyone that works out with weights knows what it feels like to be pumped, or as the kids are saying these days: swole!
The physical sensation and appearance is a result of the literal pumping action of contracting and extending muscles repeatedly under the load of a barbell, dumbbell or machine.
This action traps blood in the muscle thereby keeping the oxygen and nutrients in the local area of the working muscle tissue for up to a few minutes. It’s one of the key processes within anaerobic exercise.
Vasodilation, aka the widening of blood vessels, to allow for more blood to flow to the working muscles is as natural a process as the trapping of blood in the muscles themselves.
However, it can be enhanced by introducing the right ingredients to the body at the right time.
The supplement industry has been focused on L-Arginine for providing the muscle pump to its customers for years, and there is sound reasoning behind it.
L-Arginine is a pre-cursor to Nitric Oxide (NO) which is responsible for relaxing the walls of the blood vessels, thereby opening them up for more blood flow.
Unfortunately, more recent scientific research has demonstrated that consuming supplemental arginine for this purpose is fairly redundant because arginine is broken down so quickly that it only really provides an initial spike in blood arginine levels.
Citrulline, on the other hand, is converted to Arginine in the kidneys and so provides a long, steady release of arginine over time, which sustains the plasma concentrations and the all important muscle pump for the duration of a workout.
That means consuming Citrulline is better at elevating blood arginine levels than consuming arginine itself.
Furthermore, direct arginine supplementation can stir the bowels up a little and cause some unwanted toilet visits. Not conducive to a quality workout.
Citrulline does not cause this intestinal problem.
Bigger, longer lasting muscle pumps means bigger, longer lasting hypertrophic sets in the gym, which in-turn means greater muscle growth in the recovery stage.
There are other benefits to muscle building and recovery when supplementing citrulline:
- Muscle soreness is reduced noticeably in the two days after a workout
- Fatigue is reduced during exercise and also independent of exercise
- Growth hormone production is increased. This has been noted with arginine too but of course the longer, steadier release of arginine via citrulline supplementation would result in even more HGH activity.
How To Use Citrulline and Citrulline Malate
We’ve talked about pre-workout supplements enough by now that you probably get the gist. Usually, Citrulline (in whatever compound form) will be bundled in with a bunch of other ingredients that are deemed pro muscle.
And that’s a good thing because once the blood starts pumping to your working muscle groups, you’ll not only be getting oxygen and regular nutrients to them but also the rest of the pre-workout inclusions with them.
This sort of highlights the whole point of pre-workouts if we’re being honest. Vasodilating, swole-inducing, muscle pump ingredients are an integral part of a pre-workout supplement powder. If yours does not include at least one, preferably citrulline, we’d be asking why not.
It’s not a space saver that’s for sure. Current research suggests 6 grams (6000mg) up to even 10 grams (10,000mg) of Citrulline Malate is needed to give you a decent pump.
We’re a little more lenient and reckon that if you have at least 4 grams in your pre-workout, you will get your swole on.
Of course, if there are a couple more pump agents in there then the citrulline can afford to be a little lighter but we wouldn’t pay much attention to anything below 4 grams (4000mg).
Arginine, most often displayed as L-Arginine on ingredient labels, is still found in many pre-workout supplements and Growth Hormone boosters.
It is inferior in every way to Citrulline / L-Citrulline supplementation because although it is the important amino acid for vasodilation and other effects, it is not the best form to transport it into the body, as we’ve discussed above.
If however you find arginine alongside citrulline, it has likely been included to provide the initial spike of plasma arginine concentrations, after which the citrulline will take over.
The only way arginine would be useful for getting swole in the gym would be to consume some every five minutes in an intra-workout supplement. And even then, we think citrulline is probably superior.
Look out for Agmatine
It’s early days as far as scientific research into agmatine goes, but that doesn’t bother supplement companies, who are already putting it in their pre-workout powders.
Agmatine is a metabolite of Arginine, hence its inclusion in this discussion. For human effects, there is virtually no research but it looks promising for a couple of benefits including treatments for depression and pain.
The effect we’re more excited about is its interaction with Nitric Oxide and potential positive effect on bloodflow. Again though, we might be talking too soon.
The kicker for the supplement companies is that the effective dose of agmatine looks to be a lot lower than citrulline’s Where you need 6 to 8 grams of Citrulline Malate, Agmatine might be effective at 1 to 1.5 grams.
That means more space for other stuff in the pre-workout, or more room for profit margin, depending on how cynical you are.
Citrulline is the chief muscle pump ingredient, until it gets dethroned by something else, possibly Agmatine, in the future.
Now that you know how it works in comparison to Arginine, hopefully you feel better informed for the next time you are shopping for a new pre-workout supplement.
It’s easy to make the mistake of thinking arginine is the master of swole because inside your body it actually is.
Sometimes, and this is one of those times, it comes down to fancy biochemical science and some solid clinical trials to show us that another approach works better.
In the case of getting pumped in the gym, Citrulline is better than Arginine at boosting your arginine levels.