Citrulline Malate or Pure Citrulline – Latest Research

Citrulline Pre-Workout Supplement

A recent study has shown that Citrulline Malate might not be the solid go-to pre-workout muscle pump and endurance supplement it’s widely purported to be.

We have written an article on Citrulline written before the latest research as emerged. We have tagged it on to the bottom of this article so you can compare the differences between Citrulline Malate and Pure Citrulline

Citrulline Malate In Bullets

  • German Volume Training was used – that should be where Citrulline Malate is right at home. Instead it showed no benefit
  • Subjects were advised to continue their current supplementation (but no recording of said supplementation was made – what about interactions etc?)
  • Analysis of supplement (and others) showed higher levels of Malate than written on product label
  • This study is negative press for malic acid, citrulline and citrulline malate
  • This makes 5 major studies showing no effect of CM and only 3 studies showing positive effect
  • It’s odd to have a run of positive outcomes and then a run of negative ones. More investigation is required
  • Citrulline still provides muscle pumps, and getting swole has long term advantages of its own
  • I recommend that you try a couple months with 6 grams (citrulline) or 10 grams (CM) a half hour before training and then perhaps come of them for the same period and see if you notice anything, in performance, muscle pumps and gains
  • Nothing is set in stone. Study results conflict with one another. If you find the supplement helps you, carry on using it.

It’s my aim to explain the most recent study a little and have a look at some other investigations involving this ingredient.

I’m going to discuss whether you might look at other products for your pre-workout pump and stamina benefits.

Also relevant is my take on the industry’s apparent corner-cutting when it comes to vulnerable ingredients like Citrulline Malate that are basically a combination of two compounds.

Finally, you might be wondering – as I did – whether pure citrulline still has a place, even if Citrulline Malate does not.

Citrulline Malate – Recent German Training Volume Study

The scientific investigation was relevant as it involved a resistance training protocol called German Volume Training – or GVT.

That’s basically 10 sets of 10 reps at 70% of the subjects’ 1RM (one rep max).

GVT should be right up Citrulline Malate’s street, what with the muscle stamina aspect of the exercise protocol.

Compared with placebo, however, it outright failed to improve the subjects’ performance.

Other Studies on Citrulline Malate

In previous studies involving resistance training, the opposite has been the case. These are three of the first four studies which investigated the use of CM as an ergogenic aid in resistance training:

  1. Pérez-Guisado et al, 2010
  2. Wax et al, 2015
  3. Glenn et al, 2017

In fact, there have been 8 truly applicable studies on CM since 2010 and after the first three or four, things were looking great. They mostly concluded that it was a useful ergogenic aid.

Things took a turn in 2016 and several subsequent studies have reported that it has no effect.

  1. da Silva et al, 2017
  2. Gonzalez et al, 2017
  3. Farney et al, 2017
  4. Cunniffe et al, 2016; and
  5. Chappell et al, 2018 (this is the GVT study in 2018)

What’s more, the most recent GVT study in 2018 analysed some commercial CM products and found their ratio of citrulline to malate was not quite up to par with the label’s description.

What is the Best Pre Workout Supplement

We have tested the most popular and best performing pre workout supplements.

“I’ve tested so many I’ve lost count. To whittle them all down to a short list was no easy task, but I put my ruthless cap on and got to it.”

Find out which brands make our top 3 here

Citrulline Malate – What’s The Malate Part Mean Anyway?

L-Citrulline is a non-essential amino acid. This, as you probably know, is used as a sports/training supplement by itself.

When it is bound with malic acid, it becomes Citrulline Malate.

Malic acid is not simply a “filler” as a lot of people perceive it. There is research to show that it may have performance enhancing benefits itself due to its role in transporting energy substrates into muscle cells.

Combined with Citrulline’s reported benefits of fatigue reduction, nitric oxide production, increased blood flow and decreased muscle soreness, malic acid fits well.

Usually the two are in a 2:1 ratio or 1:1 ratio and this must clearly be stated on the label. As this study discovered, what the label says and what the actual ratio is might be two different things.

a pot of supplements

Naughty Supplement Manufacturers

It isn’t the first time supplement manufacturers have been called out for stiffing their customers, if that is indeed what they are doing.

It’s cheaper to cut L-Citrulline with Malic acid, and even cheaper to throw it in a pre-workout tub at a greater ration than it says on the label.

Unfortunately we can’t blame the negative outcomes of studies on possible company meddling because:

  1. other studies did not do the chemistry analysis; and
  2. the citrulline malate in the GVT study was at least half citrulline and considering they used 8 grams total that still leaves 4 grams of citrulline, which should be enough to have an effect

Which begs the question: what about pure L-Citrulline? Where does that feature in the grand scheme?

What About Pure L-Citrulline?

I’ll come back to Citrulline Malate in a minute, but let’s just think about good old L-Citrulline first.

Funnily enough, there aren’t many studies involving citrulline in isolation, humans and resistance training.

To be honest, it shouldn’t make that much of a difference whether it comes with malic acid or not. The dosage, however, might.

L-Citrulline increases levels of Nitric Oxide, that much is evident. It’s replaced L-Arginine as the main muscle pump ingredient, since arginine is rapidly broken down leaving little to make it to the blood stream.

Conversely, citrulline gets all the way to the kidneys, largely intact. There it is converted into arginine which is free to entire the bloodstream and increase Nitric Oxide levels.

Therefore, supplemental citrulline is a better blood arginine booster than arginine itself.

All of this to say that L-Citrulline enhances NO which enhances vasodilation and the hyperemic effects of resistance training.

In other words: it’s a muscle pump ingredient.

Why is this important?

It’s important because scientific studies don’t really focus on muscle pumps. They are focused on whether the supplement provides ergogenic/performance benefits.

Vasodilation – the blood vessel widening mechanism behind the pump – is said to be beneficial during resistance training because it allows for more blood, oxygen and nutrients to travel to the working muscles.

The next little bit is opinion-based by the way. In non-scientific terms – I’m spitballing.

Say you’re way into your last few reps of a big GVT session, are you getting much oxygen anyway?

No, you’re deep into anaerobic respiration and lactate has become your frenemy. ATP production has dramatically reduced and you feel like your muscles, heart and lungs are going to explode.

You’re pumping more blood to your muscles anyway though because you’ve got more nitric oxide and you’re swole AF.

We’ve known for a long time that the mechanical action of concentric and eccentric repetitions under load is what basically causes the pump in the first place. It literally pumps blood into your muscles. The NO boost simply augments this action.

We also know that getting pumped is one of the stimuli for a post-workout anabolic reaction cascade. Basically, despite your pump deflating within a couple hours of leaving the gym, it does help you increase muscle size over the long term.

The anabolic trigger is thought to be due to the intra-muscular cellular pressure that a good muscle pump exerts.
You won’t see this benefit in a scientific study because they don’t last long enough for them to be observed.

What I’m saying is: using citrulline – and getting swole from it – has more to it than the increased stamina and reduced muscle soreness etc.

Muscle pumps are not just a fleeting benefit of nitric oxide boosters that are good for mirror selfies and little else. They actually contribute to the long-term goals of the user, which for most gym rats is getting jacked!

At least, that’s my opinion.

Dosage of Citrulline and Citrulline Malate

If my logic makes sense then around 6 grams (6000mg) of Citrulline should be the average male’s target dose, according to the Nitric Oxide studies.

It also means that you shouldn’t rule out Citrulline Malate yet, after all, it still contains citrulline.

However, to account for some manufacture fudgery and the reduction of citrulline itself you should take about 1.8 grams of CM for every gram you would take of pure citrulline.

That makes your CM dose about 10 grams – not often found in pre-workout supplements…which brings me to my next point.

Combination with Other Ingredients

As I mentioned earlier, the latest scientific study didn’t record what the subjects were doing with respect to other supplementation. They were told not to change their usual routine in case any modification had an effect on performance.

On the other hand, in different studies, subjects are often made to abandon all other supplements so that any results can be attributed to the product being tested.

Both of these circumstances present problems that can eek into the results.

One study I’d like to see is Citrulline’s effect when combined with other pre-workout ingredients, particularly energy ingredients whose effect might be enhanced due to increased vasodilation.

The study would be long, involve incremental additions of individual ingredients, and end up being too expensive to run.

Theoretically, however, we might find out that citrulline is immensely useful in combination with other ingredients, even at lower dosages.

Certainly, this is the route many of you will go anyway, given the pre-workout supplement market is dominated by products containing blends of ingredients.

Citrulline Malate

Alternative Ingredients to Citrulline and Citrulline Malate

In case you hadn’t noticed, I think a good muscle pump is incredibly valuable. Not only does it make you look jacked in the gym, thus boosting your confidence and other fuzzy emotions that make us happier, but it has long term benefits too, especially when it happens regularly.

Over the past few years I’ve seen a number of ingredients hit the pre-workout section of the supplement stores, to the point where there are now dedicated “pump” pre-workout powders and pills.

I like this trend because said products are often stimulant-free, meaning you can heap a scoopful into your stim-riddled pre-workout and go to town.

Yeah it’s more expensive having two products but the pump product gives so much more purpose to those stimulant-heavy-nutrient-light powders, the extra cost might just be worth it…for the gains.

So, to the ingredients. Here’s what to look out for.

  • Norvaline: inhibits arginase from breaking down serum arginine which theoretically keeps arginine around for longer to keep increasing nitric oxide levels. It’s meant to work synergistically with citrulline and arginine since they raise blood arginine.
  • Agmatine Sulphate: a metabolite of L-Arginine and so far there isn’t much clinical data on its use to increase blood flow but nearly all the supplement companies are diving on it and anecdotal reports seem to concur.
  • Beetroot Powder/Juice: a natural alternative growing in popularity. It’s a rich source of nitrates and nitrates supply substrate for the NO boost. It contains natural NO3, which is inorganic nitrate.
  • Glycerol: draws fluid into cells making them and your muscles swell. Companies are getting much better at creating stable, non-clumpy, versions.
  • Glutathione: NO breaks down very quickly in the blood, meaning ingredients need to keep working in cycles to maintain the NO boost. Glutathione and citrulline have been studied together and the former appears to improve the effects of the latter.
  • Arginine Silicate (Nitrosigine): Patented combination that is supposed to take effect after minutes and last for up to 6 hours.
  • Arginine Nitrate (NO3-T): another variant of arginine which obviously brings the nitrate group to arginine which already boosts NO.

Norvaline, Agmatine, Nitrosigine and NO3-T can work at doses that fit in pills, therefore if you see “pump” products that are in capsule form, they aren’t necessarily complete crapola.

Personally, I still enjoy drink powders crammed with all of these and more. Glycerol of old is no more. It was terrible and you needed grams and grams of the stuff. The newer stabilized forms are much better.

Citrulline Malate for muscle pumps

Conclusion: Pay More Attention and See For Yourself

Pro bodybuilders and other athletes pay attention to the little details. It’s one of the reasons they get to where they are.

If you live and die by the results of scientific studies then you will be changing your training methods, nutrition and supplemental routine as often as the sun comes up.

You will benefit from making a concerted effort to observe the effects different approaches have on your results. This definitely applies to supplements.

It can’t be done overnight because products need a good period of time to take effect, and you need to take measurements and learn to tune into your body’s adaptations.

Simply put, you need to figure out if you miss something when you’re not taking it, or if you don’t really need it when you are. If nothing else, it’ll save you money.

I can see many of the industry’s major players reverting to adding pure citrulline into their pre-workout blends, although CM still has a heavy presence.

Nothing is definitive yet.

Time will tell.

Citrulline, or L-Citrulline – What Does It Do

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.
[clickToTweet tweet=”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.” quote=”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.”]

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.

Citrulline Dosage

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 Supplements

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 Conclusion

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.

Leave a Comment