If you are reading this blog then you, like me are probably obsessed with trying to eke out that little extra in the gym by abusing various pre workouts. I am going to be covering a popular but often chronically under dosed, overly mixed pre workout ingredient, L-citrulline. To see if it's worth picking up or leaving by the wayside.
This blog post will be a results focused analysis of L-citrulline with little to no focus on the bio chemical mechanisms of how it works, if a deeper dive into its mechanisms is wanted then I'll make one later down the line.
Without further ado, let's get into it.
What is it:
L-citrulline is an non-essential amino acid, meaning it can be made from other amino acids present in the body. But unlike some amino acids, L-citrulline is not used to make protein, it is instead has a role in protein homeostasis[1] and as an intermediary in the urea cycle, the process in which our bodies handle ammonia.
What does it do:
l-citrulline increases NO biosynthesis indirectly by increasing l-arginine synthesis, which in turn leads to improved blood vessel vasodilator function, aka increased pumps. [2][3][4] l-citrulline is not processed in the liver, unlike other amino acids like BCAA's which are poorly metabolised [5], but synthesised in the intestine and kidneys preventing hepatic uptake of precursor amino acids (arginine, glutamine) activating the urea cycle preventing amino acid catabolisation. The preserving nature of l-citrulline in this cycle has a down stream effect in protein synthesis, content and functionality. [6]
Practical application:
What it does is all well and good, but what about practical application and real word efficacy.
blood pressure reduction from 4-15% after 8 weeks of supplementation at a very low dose. Though L-citrulline should not be used as a replacement for medication, if you are looking for something to help manage your blood pressure then L-citrulline may add benefit here. I did not track my blood pressure during my time using only L-citrulline.
Increased muscle blood flow induced by L-citrulline has been shown to be as high as 11% in one study at 6g per day. I couldn't find studies measuring intramuscular vassal dilation at higher does of L-citrulline unfortunately. However anecdotally when supplementing with 10g of pure L-citrulline not the malate mix over a period of 8 weeks I measured a consistent visual pump that was greater than when experimenting with 6g as touted in the study.
the cited study showed a 52.92% increase in total work done with pectoral loading with 8g of L-citrulline malate, the mix ratio was not specified, though the most common is 1:2 giving roughly 5-6g of L-citrulline per serving. Though anecdotally I can give credence to the muscular endurance properties of L-citrulline, because this was mixed with malic acid that can help with lactic acid build up, the 53% increase in work load may be a byproduct of this mix.
supplementing at 1.5g for 1 month men with mild erectile disfunction reported hardened erections while supplementation occurred. Like with the blood pressure L-citrulline should not be used as a replacement for any medication being used with ED, however it may be useful as a potential adjunct. Anecdotally I don't have an issue here so didn't notice anything above and beyond what is normal, if you're looking for a replacement for viagra, you wont find it here.
supplementing from 10-22g of L-citrulline directly relating to the participants body mass showed a significant increase in protein synthesis which is a potential reason why an increase in lean mass in trainees has been observed in other studies.
Post resistance training participants reported greater reduction in muscular soreness 24-48 after. So if you are fairly new to the gym or changing up your routine and getting DOMS then L-citrulline may help.
Lean mass was shown to increase over a period if 8 weeks in a group supplementing with 2.5g of L-citrulline in comparison to those who supplemented with L-citrulline malate at 2.5g or the placebo. An average of 2.4lb lean massed gained was observed over the 8 weeks which is pretty significant. Anecdotally I used L-citrulline during a body recomp training block and though made changes to my physique I cannot purely attribute this to L-citrulline.
Dosing:
Clinical dosing of L-citrulline has ranged from as low as 0.5g to as high as 22g, making it fairly hard to directly pin point the dose at which we start to get diminishing returns or no increase benefit at all. Some studies suggest scaling L-citrulline intake to lean body mass as you would do with measuring protein intake. Anecdotally I found most success at 10g at 110kg of body weight at a roughly 11% ratio, though some may find more or less is beneficial.
When to take
No studies that I can find suggest an optimal time to ingest L-citrulline in a pre workout context, though inferring from popular opinion anywhere between 30-60 mins pre workout seems fine. Anecdotally 10g 30 mins pre workout has worked well for me.
Side effects
L-citrulline has been shown to have no negative side effects with doses as high as 15g and past that there hasn't been any effort to ascertain what, if any, side effects present themselves.
The bottom line
L-citrulline is fairly expensive as a supplement so I suggest going for a milder dose initially and slowly titrate the dose until you find what works for you.
Personally I would highly recommend L-citrulline if you have some cash to spare and want to get the most out of your training.
If you like what i'm doing here, subscribe to my mailing list and join me next week as I examine the ingredient often paired with L-citrulline, Malic acid to see what role, if any it has in muscle growth and body composition.
Laters,
Harry
P.s
Well, this has been a wild ride... I now sell my own batch tested L-Citrulline. Mad.