The most experienced strength athletes and athletes know the so-called “pump amino acids”. Most boosters contain citrulline for the benefits of a greater pump.
One of the most prominent representatives is certainly also classic L-arginine.
But why is citrulline so popular in recent years?
This has two main reasons:
Citrulline is able to increase the plasma concentration of arginine more efficiently and for a longer time than arginine itself!
Also, Citrulline is able to increase endurance and delay fatigue.
… and the latter will be the main focus today.
What is L-Citrulline?
As already described, the amino acid L-citrulline is produced as a metabolite of the amino acid ornithine (by combination with the anhydride carbamoyl phosphate) in the urea cycle.
In order to understand how L-citrulline delays fatigue, you should know that physical activity (such as strength training) produces additional metabolites (called “metabolites”) that eventually make the muscle “dense”.
You’ve already noticed that much during the workout when you’ve reached your limits. One of these metabolic products that cause muscle fatigue is ammonia (NH3).
Ammonia itself consists of three nitrogen molecules.
Now guess what the task of the urea cycle is?
Right! The filtering out of nitrogen waste. Inside the muscle, glutamine is an option for fixing (and removing) excess ammonia. L-citrulline is another way to get rid of too much ammonia.
Further studies have shown that high levels of citrulline are able to increase the concentration of arginine.
Since we are dealing with a cycle, citrulline is produced in the production of nitrogen (NO synthesis) from arginine.
It is now no secret that more NO in the body leads to better blood circulation (pumping) and thus also a positive influence on the nutrient supply of the musculature as well as the removal of waste products (for example ammonia).
The consequence: More nutrients for the muscle + faster removal of inhibiting metabolites = more endurance, less fatigue.
When you keep your eyes and ears open for a good source of L-citrulline, you quickly realize that you can rarely buy this pumping amino acid in its purest form. It is usually sold bound to malic acid (2-hydroxy succinic acid – also known as “malic acid” or malate).
Malate is a naturally occurring salt, which i.a. found in apples and provides for the sour taste of the same.
Why do the supplement manufacturers do that?
Quite simply: It ensures that the whole compound in the body is stable and the citrulline arrives where it is supposed to go.
The interesting thing is, however, that malic acid has an “anti-fatigue” effect on its own, as it helps the body to recycle the lactic acid produced during exercise.
L-Citrulline Malate against Fatigue and Sore Muscles
Malate acts as a stabilizer and has its very own benefits, e.g. an anti-exhausting effect.
As soon as you go into the gym and start your training, you start to change the milieu in the muscle environment – the pH drops. Once the muscle is heavily acidified, it can not do any more work, it is exhausted.
But what is the relevance of L-citrulline malate in practice?
Fortunately, Spanish researchers have asked a similar question, and in an experiment with male strength athletes, investigated the effect of supplementation with L-citrulline malate in a bench press.
The 41 participants received either a placebo or the supplement before the workout, and interestingly, the number of repetitions in the CM group increased by 52.92% over the placebo.
Candidates who received the supplement reported a lower level of muscle soreness at the respective time stamps (24 & 48 hours post-workout) (specifically: 40% less).
Only side effect? 14.63% of CM supplementators reported abdominal grumbling.
Another team of researchers investigated the effects of CM supplementation on professional cyclists – a group of athletes not well known for their low training load.
It is known that high volume leads to impaired activity of the immune system, thus increasing the risk of infections (e.g., respiratory diseases).
The Spaniards found out in this study that citrulline malate mitigates the immunosuppressive (inhibitory) effect of a high training volume.
This find is likely to be of particular interest to the volume lovers among us, who often struggle with colds and infections and who very often scratch overreaching (precursor to overtraining).
Citrulline and Growth Hormones
In a study that gave athletes 6 g of L-citrulline before a long bike ride (137 km), it was shown that growth hormone release was 28% higher as a result of training than training alone.
However, another study failed to show such an effect when no physical activity followed.
These results suggest that L-citrulline only enhances the exercise-induced increase in growth hormone release and does not generally lead to increased release of the hormone.
Ingestion of 18 mg / kg L-citrulline for one week could not increase IGF-1 in another study.
Citrulline and Potency
In patients with erectile dysfunction, L-citrulline increased potency.
Among other things, it has been shown that 50% of men who suffer from erectile dysfunction and were given L-citrulline subsequently had a harder erection than before.
In addition, as taking L-citrulline in our body increases L-arginine levels, other effects on potency are also likely. Studies investigating the effect of L-arginine on potency show promising effects.
L-Citrulline and the Immune System
In the scientific study of Sureda and his colleagues, citrulline led to an increase in the so-called oxidative burst.
The oxidative burst is a function of our immune cells that can neutralize bacteria, viruses and other undesirable things.
This can lead to an improved immune response.
Side Effects of Citrulline
L-citrulline appears to be associated with fewer side effects than L-arginine.
Thus, a study shows that the administration up to 15 g does not lead to diarrhea or other side effects such as gastrointestinal problems.
The whole thing could be because L-citrulline is better absorbed than L-arginine.
However, in the aforementioned study examining the effect of L-citrulline malate on weight training, some subjects had gastric problems. However, this side effect occurred only in a rather low percentage of subjects.
People who suffer from cardiovascular disease or other conditions should talk to their doctor first about ingestion because of potential side effects.
Best Citrulline Dosage
To achieve positive effects on the health of the cardiovascular system, it is sufficient to take 1000 mg of L-citrulline three times daily with meals.
Most of our readers, however, certainly want to use the amino acid to have a positive effect on strength training. Useful dosages for this range from 6000 to 8000 mg in the form of L-citrulline malate.
Arginine or Citrulline?
Classic arginine dominated the supplement market as a NO booster just a few years ago.
However, this changed very quickly, after a German research team was able to work out the potency of citrulline malate: Already 3g of citrulline malate were enough to increase the plasma arginine level significantly, while 6g of arginine did not lead to a positive result.
“Citrulline supplementation significantly increased plasma concentration of both arginine and citrulline after the stage only in the supplemented group.”
When it comes to personal assessment and practical experience, we recommend a combination solution of AAKG and CM to achieve a long-lasting effect and improved blood circulation.
If the digestion with arginine is digestive, a shift should be made in favor of citrulline malate (until complete elimination of arginine, if better tolerated, without diminishing effects).
Whether you choose AAKG, OKG or CM is up to you.
The facts presented here, however, show impressively, which benefits are expected to be supplemented with the so-called “pump supplements” (more intense workout, less fatigue, and improved regeneration).
Do you take L-Citrulline?