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Citrulline is not as well known in sports nutrition as protein or creatine, but it definitely deserves attention. It is especially popular with strength athletes who take it before training with the goal of pumping up their muscles. However, they don’t do it just to look bigger and crave the admiring glances of other gym-goers. Thanks to muscle pumping, they’ll have the area in question well perfused with blood, which will translate into improved strength performance. But the effects of citrulline are far from over. In fact, it offers a number of benefits for strength and endurance athletes and also has interesting health benefits, which you will discover today.
In this article you will read about the effects of citrulline on these specific areas:
What is citrulline?
Citrulline is a non-essential amino acid that the body can make itself. In the body, it is produced as an intermediate from the amino acid ornithine and carbamoyl phosphate as part of the urea cycle. At the same time, you naturally ingest it from certain foods or supplements. Unlike other amino acids you know from sports nutrition, citrulline is not used in the body as a building block for the growth or regeneration of muscles and other tissues. However, it has a completely different function that is just as important for athletes. [3]
An interesting fact about citrulline is that the name was derived from the Latin word citrullus vulgaris, which translates as watermelon. It was from watermelon that the substance was first isolated in 1914. [7]
If you are interested in other amino acids and want to learn more about their effects, read our article Amino Acids: Classification, Functions in the Body, Effect on Athletic Performance and the Best Sources.
How does citrulline work?
Citrulline is involved in two key processes in the body. The first is the aforementioned urea cycle. This takes place mainly in the liver and is important for the removal of toxic ammonia from the body and its conversion to less toxic urea, which is then excreted in the urine. In addition to citrulline, ornithine and arginine are also involved in this detoxification process. In this way, citrulline is involved in processes related to the body’s natural detoxification. [1, 3]
The second process, which will be of greater interest to athletes, is the production of nitric oxide (NO). Citrulline can be converted into the amino acid arginine in the body. From this, nitric oxide is then formed, which has the effect of dilating blood vessels (vasodilation). This allows better blood flow to the tissues, which results in a greater muscle pump. This allows more oxygen and other nutrients to reach the muscles, and also results in more efficient removal of waste products of energy metabolism. All of this can result in better athletic performance.
2. Muscle growth
Although citrulline does not build muscle, it can still support the whole process of building active body mass. Scientists have found that it can activate the mTOR (Mammalian Target of Rapamycin) signalling pathway, which is at the origin of processes related to cell growth (muscle growth and anabolic events) and muscle protein formation MPS (Muscle Protein Synthesis). [1]
In addition, citrulline can promote the use of other amino acids, especially leucine, isoleucine and valine (BCAA) during exercise. This in turn can help to suppress catabolism (the breakdown of muscle tissue). The positive effect on muscle protection and growth is probably also due to an increase in growth hormone levels, which has also been observed when taking citrulline. [11]
In addition, it has been found that under energy-intensive conditions (insufficient energy intake, high energy expenditure), citrulline can redirect energy in the form of ATP, which is produced in the mitochondria, to be used for muscle formation. [12]
But you must not forget one more factor that can play a significant role in building muscle mass. When you train longer, at a higher intensity or do more reps with heavy weights as a result of taking citrulline, your muscles get a bigger training boost than without it. The body then responds to this load with adaptive processes that lead to muscle growth. Thus, the principle of progressive overload, which is the alpha and omega of building muscle mass and improving performance, is fulfilled.
What can you combine citrulline with to promote muscle growth?
You can also support building active mass with other nutritional supplements.
- Protein: A concentrated source of protein that promotes muscle growth as well as muscle protection.
- EAA: Contains essential amino acids that your body cannot produce on its own. They are used to form muscle mass or hormones.
- Gainer: A protein and carbohydrate complex to help increase energy and protein intake.
If you are trying to gain muscle and are wondering how to boost this, then you should not miss our article What to Eat and How to Exercise to Finally Gain Muscle?
Side effects of citrulline
In the event that you are healthy and take citrulline as recommended, you do not have to worry about side effects. It is a safe substance that is inherent to your body, but if you are being treated, for example, for high blood pressure or taking heart medication, you should consult your doctor about the suitability of citrulline. [22]
How much citrulline is too much, you may ask? It is not to be taken in excess, but the safety of citrulline has been confirmed in studies with a daily dose of up to 15 g. However, it is sufficient if you stick to the above-mentioned dosage.
What should you remember?
Citrulline is one of those supplements that are worth taking if you want to improve your athletic performance. It pumps up your muscles, which will be better supplied with oxygen and nutrients, while taking care of waste removal. This can be seen through improved performance at the gym as well as greater regeneration. It can also be beneficial for heart function, blood vessels and male sexual health. However, you should always consider your overall lifestyle and not rely on just citrulline alone.
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[12] Goron, A., Lamarche, F., Blanchet, S., Delangle, P., Schlattner, U., Fontaine, E., & Moinard, C. Citrulline stimulates muscle protein synthesis, by reallocating ATP consumption to muscle protein synthesis. – https://doi.org/10.1002/jcsm.12435
[13] da Silva, D. K., Jacinto, J. L., de Andrade, W. B., Roveratti, M. C., Estoche, J. M., Balvedi, M. C. W., de Oliveira, D. B., da Silva, R. A., & Aguiar, A. F. Citrulline Malate Does Not Improve Muscle Recovery after Resistance Exercise in Untrained Young Adult Men. – https://doi.org/10.3390/nu9101132
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[21] Examine. Which foods are rich in citrulline? – https://examine.com/supplements/citrulline/faq/which-foods-are-rich-in-citrulline/
[22] Papadia, C., Osowska, S., Cynober, L., & Forbes, A. Citrulline in health and disease. Review on human studies. – https://doi.org/10.1016/j.clnu.2017.10.009
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