Citrulline Uses and Benefits For Bodybuilding
How Can Citrulline Improve Athletic Performance?
LAST UPDATED: September 2018.
Author: Nicola Joyce is a member of the National Union of Journalists and the Fitness Writers Association.
Much of her writing regarding fitness is built upon fist hand experience having competed internationally as a natural bodybuilding, endurance athlete and power lifter.
This review of citrulline is supported by scientific studies references at the footer of the page.
Amino Acids and Fitness
The amino acid l-citrulline can help you get better results from your training.
Here’s what you need to know about citrulline.
We’re all here for the same reason: because we want to be bigger, better, and stronger. But are you maximising how you use simple, natural supplements? If you’re not using citrulline, you could be missing a trick.
Read on to discover more about this amino acid and how it can boost your training performance so you can make better gains.
What Exactly Is Citrulline?
Citrulline is one of the non-essential amino acids. As you know, amino acids are considered the “building blocks” of protein.
They are crucial for building, maintaining, and repairing all tissue and cells, including muscle.
In the human body, the kidneys convert l-citrulline into the amino acid called l-arginine plus the chemical called nitric oxide (NO).
Arginine is an essential precursor for NO and creatine.
However, citrulline is actually more effective in increasing l-arginine than l-arginine supplementation itself.
Citrulline vs. Arginine
Supplementing with arginine will increase plasma arginine, but citrulline supplementation increases it for longer.
Arginine is predominantly used by the liver, whereas citrulline can be taken up by the entire body.
You’ve probably heard of nitric oxide (NO) as a performance enhancing ingredient in many pre-workouts. Citrulline’s role in NO production should tell you why it’s important to training performance.
You’ll find citrulline supplements referred to as l-citrulline (which is the free form version of the amino acid) or citrulline malate (which is the amino acid, attached to a magic acid molecule).
How Does Citrulline Impact Bodybuilding?
Citrulline plays an important role in heart health, blood vessel health, and immune system strength.
Its cardiovascular effects help optimise blood flow, meaning you’ll be able to train harder, offset fatigue, and fill muscle cells with more blood.
This doesn’t just mean a good pump (although that’s important!) Cell swelling is key for hypertrophy and muscle gain over time.
Citrulline produces nitric oxide in the body, and this dilates blood vessels to boost oxygen and nutrients to your working muscles, and help with the removal of metabolic waste.
Think of citrulline as the amino acid which kickstarts a series of performance-boosting functions which help your muscles work better, grow more, and recover faster.
What Foods Contain Citrulline?
Fun fact: the name citrulline comes from the Latin word “citrullus”, meaning watermelon.
Go to the top of the class if you deduced that watermelon is naturally high in citrulline.
In fact, watermelon is the only food source significantly high in citrulline.
So unless you’re a watermelon super-fan (and prepared to eat a lot of it all year round), you’ll need to supplement with a citrulline product.
You’d need to eat around 3.3kg watermelon to get the equivalent of 10g supplemental l-arginine. 
How Much Citrulline For Athletic Performance Benefit?
There have been plenty of studies into the effects on citrulline on athletic performance, but none of them give a standardized recommendation for intake.
For example, this is an old study (1985) but it looked at the role of citrulline and arginine in stimulating nitric oxide synthesis during intense exercise.
The dose was done on bodyweight, but translated to around 0.08g/kg bodyweight of citrulline.
This study showed that citrulline supplementation improved the athletes’ tolerance to intense exercise, and helped them do more work.
It concluded that short-term citrulline supplementation may have a positive impact on blood pressure, and improve training performance. 
Another study found that supplementing with 8g citrulline one hour before training resulted in an increase in resistance training performance, lowered RPE during upper body training, and seemed to decrease DOMS after the training session. 
Importance of Citrulline?
Citrulline is non-essential, which means we don’t need to get it from food or from supplements.
But that’s not to say that it isn’t beneficial.
It’s no coincidence that l-citrulline is a key ingredient in leading pre-workouts and intra-workout blends.
If you train frequently and intensely, or if you are concerned about your cardiovascular health (or have a family history of poor blood vessel function), citrulline supplements could help your heart, blood, and CV system function more optimally.
For such a cheap supplement, it’s certainly worth a try.
Citrulline And Weight Training
Various studies suggest that supplementing with citrulline may reduce muscle soreness or DOMS during the 24-48 period after training, and that it can delay fatigue and RPE so you can increase the load, volume, or intensity of your sessions.
Effective Dose Of Citrulline
As we’ve said, there’s no single accepted recommendation for dosing citrulline.
All the studies so far base their doses on individual body weight, rather than on a blanket amount.
The current thinking is 0.08-18g citrulline per kg bodyweight per day (but the cycling study, referenced above, suggests a general dose of 6g citrulline per day).
This is a really wide spectrum, so we suggest that you experiment with dosing your own citrulline (starting at the low end to assess tolerance and effectiveness).
Citrulline supplements are available as citrulline powder, which you can mix with your own pre workout, or as citrulline capsules or tablets.
Citrulline is also present in a lot of popular pre workouts, alone or in conjunction with arginine.
Is Timing Key To Taking Citrulline?
Timing is likely to be important for taking citrulline supplements.
When you take citrulline before a weights workout, the lowering effect on your blood pressure will lead to a better pump, because more blood will l get to your muscles.
And, since the main benefit is boosting circulation and increasing training endurance, the best time to take your citrulline is probably 60-30 minutes before training.
Using it as a pre-workout, or within a pre-workout blend, is the most obvious way to use this cheap and effective amino acid supplement.
Make Your Own Pre-Workout
Citrulline is a popular ingredient for homemade pre-workout drinks. Here are a few combinations which will boost energy, sharpen your focus, and open up those blood vessels for a better pump, good nutrient uptake, and faster recovery.
5g caffeine monohydrate
6g citrulline malate
2g beta alanine
4g beta alanine
6g citrulline malate
20g-40g carbs in liquid or high GI form
A cup of strong black coffee
2g beta alanine
BCAAs containing 4g leucine
6g citrulline malate
 Elevated plasma citrulline and arginine due to consumption of Citrullus vulgaris (watermelon). Mandel H, Levy N, Izkovitch S, Korman SH. J Inherit Metab Dis. 005;28(4):467-72. PMID: 15902549
 l-Citrulline supplementation improves O2 uptake kinetics and high-intensity exercise performance in humans. Bailey SJ, Blackwell JR, Lord T, Vanhatalo A, Winyard PG, Jones AM. J Appl Physiol (1985). 2015 Aug 15;119(4):385-95. doi: 10.1152/japplphysiol.00192.2014. Epub 2015 May 28. PMID: 26023227
 Citrulline malate enhances athletic anaerobic performance and relieves muscle soreness. Pérez-Guisado J, Jakeman PM. J Strength Cond Res. 2010 May;24(5):1215-22. doi: 10.1519/JSC.0b013e3181cb28e0. PMID: 20386132
Nicola Joyce (aka “the fit writer”) is a fitness industry copywriter who has been writing for and about sport and fitness since 2004. Nicola is a competitive drug-free bodybuilder (with two World titles at amateur level) and has also competed in powerlifting and a couple of strongman comps. Prior to her strength training days, Nicola was an endurance athlete and has even swum the English Channel twice. She can be found on all social media at: thefitwriter.