The effects of citrulline

When we talk about “citrulline effect,” we're mainly discussing one goal: to perform better during training, to get a better "pump," and to sustain effort longer without crashing after 20 minutes.

Citrulline is a non-essential amino acid, naturally present in some foods (especially watermelon), but primarily known in sports nutrition for its indirect link to nitric oxide.

The idea is simple: citrulline can help the body produce more available arginine, which supports the production of nitric oxide (NO) and, in turn, better vasodilation. The potential result: improved circulation, better sensations, and sometimes more stable muscular endurance.

What is citrulline and why is it so talked about?

Citrulline is an amino acid involved in the urea cycle, a process that helps manage certain nitrogenous wastes from metabolism. In practice, its appeal to athletes primarily stems from its role as an indirect "precursor" to arginine.

Once consumed, citrulline can be converted to arginine in the body, which can increase the availability of arginine in the blood more effectively than arginine itself in some contexts. This is the basis of the famous "citrulline effect" sought after in pre-workouts.

Citrulline effect: vasodilation, “pump” and performance

The most well-known mechanism of citrulline involves arginine and then nitric oxide (NO).

NO contributes to vasodilation, meaning the ability of blood vessels to widen, which can promote blood flow to muscles during exertion. Concretely, this can enhance the feeling of a "pump" and also improve comfort during exercise, especially when sets follow one another and the muscle starts to burn.

Beware of the classic trap: citrulline is not a "stimulant" like caffeine. The sensation is often more subtle. Some people feel a clear difference in congestion and the quality of their sets, while others experience a more moderate effect. Efficacy depends on dosage, timing, and whether the training is sufficiently demanding for the difference to be noticeable.

Endurance, fatigue, recovery: what citrulline can change

Beyond the pump, citrulline is often used to support muscular endurance. In some protocols, it's associated with improved exercise tolerance and a slightly delayed perception of fatigue, especially during high-volume sessions or long time-under-tension periods.

It is therefore found in both weightlifting and cross-training, Hyrox, circuit training, or sports where intense efforts are repeated.

Regarding recovery, one must be measured: citrulline is not a "miracle" product that replaces sleep, calories, protein, and volume management. However, if it improves the quality of the session (better execution, more clean repetitions, better tolerance), it can indirectly contribute to better long-term results.

Citrulline vs arginine: why citrulline is often preferred

Many athletes ask themselves: why not just take arginine directly? Because arginine is sometimes less "efficiently utilized" once ingested, notably due to intestinal and hepatic metabolism. Citrulline, on the other hand, can lead to a more stable increase in plasma arginine in many people.

In short: if the goal is to increase available arginine to support NO production, citrulline is often a more logical choice.

What dosage and when to take citrulline?

To achieve a true "citrulline effect," most athletic protocols suggest around 6 to 8 g of L-citrulline, usually taken before training. The most common timing is 30 to 60 minutes before the session, especially if you take it alone in water.

If it's integrated into a meal, absorption may be slightly slower, so it can be taken a little earlier.

If you are new to it, the simplest approach is to be progressive. Start with a lower dose to check your digestive tolerance, then work your way up to an effective dose. The idea is not to "force" a feeling, but to establish a consistent routine for the sessions where you want to perform well.

Citrulline malate: useful or marketing?

Citrulline is very often found in the form of citrulline malate, meaning citrulline combined with malate (a salt of malic acid). This form is very popular in pre-workouts.

In practice, the main benefit remains citrulline itself, but malate is sometimes presented as a potential support for energy metabolism.

The important point is to look at the actual amount of citrulline in the product: depending on the ratio (e.g., 2:1), the "total" dose does not correspond to 100% citrulline. So if you are aiming for 6–8 g of citrulline, you need to adjust the dose according to the form used.

Side effects and precautions

Citrulline is generally well tolerated, but at high doses, some people may experience digestive discomfort (bloating, upset stomach). This is why it is often smarter to test tolerance and then gradually adjust.

If you have a cardiovascular condition, very low blood pressure, or are on medication that affects blood pressure, it is best to seek advice from a healthcare professional before regular use.

Conclusion

In summary, "citrulline effect" primarily refers to a potential improvement in vasodilation, pump, and muscular endurance, through better arginine availability and support for NO production.

To derive real benefit, the most important thing is to use a consistent dose, at the right time, and during sessions where the difference can translate into higher quality work. As always, consistency and the basics (training, nutrition, sleep) are what yield results.

Scientific sources

• Schwedhelm, E. et al. “Pharmacokinetic and pharmacodynamic properties of oral L-citrulline and L-arginine.” British Journal of Clinical Pharmacology.
• Bailey, S. J. et al. “L-citrulline supplementation and exercise performance: mechanisms and outcomes.” Sports Medicine.
• Gonzalez, A. M. & Trexler, E. T. “Citrulline supplementation and strength/endurance performance.” Journal of Strength and Conditioning Research.