Introduction
As a former collegiate athlete and current medical student, I have developed an interest in the science behind exercise-related supplementation. I am collaborating with Forca Method to discuss the compounds used in their pre-workout formula and to examine their benefit to combat sport performance. My goal is to provide a clear explanation of each compound, along with a brief literature review of the data surrounding it. The first compound I’m reviewing is L-citrulline.
Citrulline is a non-essential amino acid, meaning the body can produce it on its own. It is also found naturally in fruits such as watermelon. Unlike the amino acids that build proteins, citrulline’s primary importance lies in its ability to increase circulating arginine, which in turn supports nitric oxide production. So what does this mean in practice? Nitric oxide is a signaling molecule that relaxes—or vasodilates—blood vessels. When vasodilation increases, blood flow to working muscle improves, supporting the delivery of oxygen and nutrients to active tissue while facilitating the clearance of fatigue-related byproducts, such as lactic acid, during intense training. It’s worth noting that citrulline supplementation raises blood arginine levels far more effectively than ingesting arginine directly, because arginine is frequently broken down before it enters systemic circulation.
What Does the Research Say?
The most widely accepted rationale for citrulline supplementation is its ability to increase arginine availability and, by extension, nitric oxide (NO) production. A 2022 review of several amino acids used in sports nutrition reported that 2.4–6 grams of citrulline per day over 1–2 weeks significantly increased NO production and physical performance markers across the studies reviewed (Nyawose et al., 2022). Within that review, several studies are particularly relevant to combat sports. Terasawa and Nakada used a double-blind, placebo-controlled design with nine male collegiate track athletes. Participants took 3 grams per day of L-citrulline for 7 days and then performed repeated Wingate tests on a bicycle ergometer. Citrulline improved mean power output, pedaling speed, and oxygen consumption while reducing perceived exertion—findings directly applicable to repeated high-output sports (Terasawa & Nakada, 2019). Another trial by Suzuki et al. used a double-blind, randomized, placebo-controlled design with 22 trained men. Participants consumed 2.4 grams per day of L-citrulline or placebo for 7 days, followed by an additional 2.4-gram dose one hour before a 4-km cycling time trial. L-citrulline significantly increased plasma L-arginine levels, reduced completion time by 1.5%, and improved subjective ratings of muscle fatigue and concentration after exercise (Suzuki et al., 2016).
A major systematic review and meta-analysis by Trexler et al., published in Sports Medicine, evaluated citrulline specifically for high-intensity bouts of exercise. The authors examined repetitive muscle actions of large muscle groups, including resistance training sets and sprint efforts lasting 30 seconds or less. They found that citrulline produced a statistically significant benefit over placebo for repetitive large-muscle-group actions (Trexler et al., 2019).
Citrulline has also been linked to improved muscle recovery following exercise. A separate systematic review and meta-analysis pooled 13 randomized controlled trials with a total of 206 participants. These studies evaluated healthy individuals and focused on the acute effects of citrulline or citrulline malate, analyzing post-exercise ratings of perceived exertion, muscle soreness, and blood lactate. Citrulline supplementation significantly reduced post-exercise ratings of perceived exertion and muscle soreness at 24 hours, though it did not change blood lactate levels (Rhim et al., 2019). For combat athletes, reduced perceived exertion may matter more than it does for traditional athletes, since training quality depends heavily on how much work an athlete can tolerate across a full session or week.
While limited data evaluate citrulline’s efficacy specifically in combat sports such as jiu-jitsu, the evidence clearly covers the demands of the sport. Increased blood flow to working tissue has been shown to improve performance in both steady-state aerobic and explosive anaerobic training, with the added benefit of reducing perceived soreness during recovery.
Relevance & Conclusions
Brazilian jiu-jitsu, wrestling, judo, and MMA are neither purely strength-based nor purely cardio-based sports. They are repeated-effort disciplines that combine short bursts of explosive output with sustained endurance—and that is precisely why citrulline is relevant. Citrulline has been shown to support repeated muscular efforts, high-intensity work capacity, fatigue resistance, and improved perception of effort and recovery. Put plainly, citrulline is a strong pairing in a pre-workout formula such as Forca Method. Combined with other performance-enhancing supplements, it delivers dependable benefits for consistent users.
References
- Bailey, S. J., Blackwell, J. R., Lord, T., Vanhatalo, A., Winyard, P. G., & Jones, A. M. (2015). L-citrulline supplementation improves O₂ uptake kinetics and high-intensity exercise performance in humans. Journal of Applied Physiology, 119(4), 385–395. doi:10.1152/japplphysiol.00192.2014
- Nyawose, S., Naidoo, R., Naumovski, N., & McKune, A. J. (2022). The effects of consuming amino acids L-arginine, L-citrulline (and their combination) as a beverage or powder, on athletic and physical performance: A systematic review. Beverages, 8(3), 48. doi:10.3390/beverages8030048
- Rhim, H. C., Kim, S. J., Park, J., & Jang, K.-M. (2020). Effect of citrulline on post-exercise rating of perceived exertion, muscle soreness, and blood lactate levels: A systematic review and meta-analysis. Journal of Sport and Health Science, 9(6), 553–561. doi:10.1016/j.jshs.2020.02.003
- Stanelle, S. T., McLaughlin, K. L., & Crouse, S. F. (2020). One week of L-citrulline supplementation improves performance in trained cyclists. Journal of Strength and Conditioning Research, 34(3), 647–652. doi:10.1519/JSC.0000000000003418
- Suzuki, T., Morita, M., Kobayashi, Y., & Kamimura, A. (2016). Oral L-citrulline supplementation enhances cycling time trial performance in healthy trained men: Double-blind randomized placebo-controlled 2-way crossover study. Journal of the International Society of Sports Nutrition, 13, 6. doi:10.1186/s12970-016-0117-z
- Terasawa, N., & Nakada, K. (2019). Effect of L-citrulline intake on intermittent short-time high-intensity exercise performance in male collegiate track athletes. The Journal of Physical Fitness and Sports Medicine, 8(4), 147–157. doi:10.7600/jpfsm.8.147
- Trexler, E. T., Persky, A. M., Ryan, E. D., Schwartz, T. A., Stoner, L., & Smith-Ryan, A. E. (2019). Acute effects of citrulline supplementation on high-intensity strength and power performance: A systematic review and meta-analysis. Sports Medicine, 49(5), 707–718. doi:10.1007/s40279-019-01091-z
Citrulline FAQ
Quick answers to the most common questions about L-citrulline and how it fits into a pre-workout designed for combat sport.
What does citrulline actually do?
Citrulline is an amino acid that raises arginine levels in the blood, which boosts your body’s production of nitric oxide. Nitric oxide relaxes blood vessels (vasodilation), which improves blood flow to working muscle. More blood flow means more oxygen and nutrients getting to active tissue, and faster clearance of fatigue-related byproducts during hard training.
Why not just take arginine directly?
It seems intuitive, but it doesn’t work as well in practice. When you take arginine on its own, much of it gets broken down in the gut and liver before it reaches systemic circulation. Citrulline bypasses that breakdown and gets converted to arginine in the kidneys, so it raises blood arginine levels more effectively than supplementing with arginine itself.
How much citrulline should I take, and when?
The research most commonly supports doses of 2.4 to 6 grams per day, taken consistently over one to two weeks for sustained benefits. For acute, pre-training use, the studies typically use a dose roughly one hour before exercise. Forca Method is dosed within this clinically supported range. Always follow the label instructions and consult a healthcare provider if you have any underlying conditions.
Is citrulline actually useful for jiu-jitsu specifically?
Yes — even though most studies have looked at cycling, sprinting, and resistance training rather than grappling directly. Jiu-jitsu is a repeated-effort sport that mixes short explosive bursts with sustained output, which is exactly the demand profile citrulline has been shown to support. The benefits most relevant to grapplers are improved repeated muscular output, fatigue resistance, and reduced perceived exertion during long rolls or hard rounds.
Will I feel it working?
Citrulline doesn’t produce the sharp stimulant rush you get from caffeine. The effect is more subtle: improved muscle pump, less “gassing out” on repeated efforts, and reduced perceived effort late in a session. Many users notice they recover faster between rounds and feel less sore the day after hard training, especially after a week or two of consistent use.
Does citrulline help with recovery and soreness?
Research suggests yes. A meta-analysis pooling 13 randomized controlled trials found that citrulline supplementation significantly reduced post-exercise ratings of perceived exertion and muscle soreness at 24 hours. For a sport like jiu-jitsu, where you’re training multiple times a week and need to show up the next day ready to roll, reduced soreness translates directly into better training quality.
Are there side effects?
Citrulline has a strong safety profile in the published research at typical supplemental doses. Most users tolerate it well. Some people may experience mild gastrointestinal discomfort, especially at higher doses or on an empty stomach. If you take blood pressure medication, PDE-5 inhibitors, or nitrate-based drugs, talk to your physician before using anything that affects nitric oxide pathways.
How long until I notice a difference?
Some studies show measurable performance benefits after a single acute dose taken roughly an hour before training. The more consistent effects on perceived exertion, recovery, and repeated work capacity tend to show up after about 7 to 14 days of daily use. Treat it like a training input: consistency matters.
Can I stack citrulline with other pre-workout ingredients?
Yes — citrulline is a foundational pre-workout ingredient and pairs well with stimulants (like caffeine), buffers (like beta-alanine), and creatine. Forca Method is formulated with citrulline as a core component alongside other performance-supporting ingredients chosen specifically for the demands of combat sport.
Is citrulline safe for tested athletes?
Citrulline itself is not a banned substance under WADA, IBJJF, or USADA. That said, athletes subject to drug testing should always verify the full ingredient list of any supplement they take, since contamination or undeclared ingredients in poorly manufactured products are the more common cause of failed tests. If you compete in a tested federation, check the most current banned-substance list and consult the supplement manufacturer about third-party testing.
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