Maximising Muscle Pump and Endurance: The Role of Citrulline Malate in Exercise Physiology

Ergogenics have always been a topic of interest for giving a competitive edge to the athletes and providing necessary aid and supplementation to their training programmes. One such over-the-counter supplement, Citrulline malate, was recently found to increase aerobic energy production, increase muscular force output , and reduce muscle exhaustion. (1) (2) (3)

Citrulline malate is a dietary supplement that combines the amino acid citrulline with the carboxylic acid malic acid. Citrulline is a non-essential amino acid found in foods such as watermelon that is spontaneously synthesised in the body and Malic acid, on the other hand, is a naturally occurring compound present in a variety of fruits. 

Let's break down these components further to get a better understanding of what exactly is Citrulline Malate.

Citrulline, once generated, is involved in several metabolic processes, most notably the urea cycle, and is a precursor for the amino acid arginine. Arginine helps to produce nitric oxide, which expands blood vessels and improves blood flow and oxygen delivery throughout the body. Because skeletal muscles need oxygen to produce energy during aerobic exercise, releasing more nitric oxide helps more functioning muscles and increases aerobic capacity. Consider taking supplements that include citrulline as a first step towards increasing your body's synthesis of nitric oxide. (4) (5) 

Malate, the ionised form of malic acid, contributes minimally to the Krebs Cycle or TCA, which is the main mechanism through which our bodies produce energy by using dietary fats and carbs. (6) (7) 

But how exactly does citrulline malate benefit our bodies? Research and increasing interest in the physiological signalling molecule, nitric oxide has some answers. 

Over a dozen human clinical studies employing citrulline malate have been reported in the last decade. Most experts believe that improved advantages for weight lifting, cycling, tennis, and muscular discomfort, to mention a few, are possible. It did not, however, increase muscular recovery in ‘untrained’ young men. (8) (9)

Ingestion of CM may aid acute recovery from exercise by increasing blood flow and indirectly increasing nutrition supply and waste metabolite elimination. This might have significant ramifications for athletes who, due to the high frequency of activity bouts in their schedules (e.g., team sports, track and field), may have inadequate rejuvenation from competition/training. (10)

The synergistic interaction of L-citrulline and malate at the metabolic level of the muscles may be responsible for the positive benefits of citrulline malate. Particularly, greater rates of adenosine triphosphate (ATP) production during exercise and an enhanced rate of phosphocreatine recovery after activity have been found. (2)

This compound has been researched for heart disease and erectile dysfunction (ED), apart from its effects on training and exercise because it improves cardiovascular performance as well (11).

Watermelon, cucumbers, muskmelons, gourds and pumpkins are some of the natural sources of CM apart from its form in supplements, but watermelon juice is undoubtedly the finest natural and whole food source of L-citrulline as each litre contains around 2.33g. (12)

If you wish to take an L-citrulline supplement, consult with your doctor first. If you've been cleared to take L-citrulline, a safe daily dose is 3 to 6 grams. Begin with the smallest amount. If you don't notice any adverse effects, you may always raise the dosage to see if it impacts your outcomes (12). 

Keep yourself updated with new and upcoming research on all kinds of side effects, benefits and consequences for supplementation of various kinds. 

Happy Training!

References 

1. Williams, M. H. (1999). FACTS AND FALLACIES OF PURPORTED ERGOGENIC AMINO ACID SUPPLEMENTS. Clinics in Sports Medicine, 18(3), 633–649. https://doi.org/10.1016/s0278-5919(05)70173-3
2. Bendahan, D., Mattei, J., Ghattas, B., Confort-Gouny, S., Guern, M. L., & Cozzone, P. (2002). Citrulline/malate promotes aerobic energy production in human exercising muscle. British Journal of Sports Medicine, 36(4), 282–289. https://doi.org/10.1136/bjsm.36.4.282
3. Pérez-Guisado, J., & FitzGerald, R. J. (2010). Citrulline Malate Enhances Athletic Anaerobic Performance and Relieves Muscle Soreness. Journal of Strength and Conditioning Research, 24(5), 1215–1222. https://doi.org/10.1519/jsc.0b013e3181cb28e0
4. Gough, L. A., Sparks, S. A., McNaughton, L. R., Higgins, M. J., Newbury, J. W., Trexler, E. T., Faghy, M. A., & Bridge, C. A. (2021). A critical review of citrulline malate supplementation and exercise performance. European Journal of Applied Physiology, 121(12), 3283–3295. https://doi.org/10.1007/s00421-021-04774-6
5. Muszalski, C. (2022, January 3). What Is Citrulline Malate? | Benefits, Dosage & Side effects. MYPROTEINTM. https://www.myprotein.com/thezone/supplements/citrulline-malate-what-is-benefits-dosage-side-effects/#what
6. Bendahan, D., Mattei, J., Ghattas, B., Confort-Gouny, S., Guern, M. L., & Cozzone, P. (2002b). Citrulline/malate promotes aerobic energy production in human exercising muscle. British Journal of Sports Medicine, 36(4), 282–289. https://doi.org/10.1136/bjsm.36.4.282
7. Biology Online. (2021, July 23). Malate Definition and Examples - Biology Online Dictionary. Biology Articles, Tutorials & Dictionary Online. https://www.biologyonline.com/dictionary/malate
8. Cunniffe, B., Papageorgiou, M., OʼBrien, B., Davies, N., Grimble, G. K., & Cardinale, M. (2016). Acute Citrulline-Malate Supplementation and High-Intensity Cycling Performance. Journal of Strength and Conditioning Research, 30(9), 2638–2647. https://doi.org/10.1519/jsc.0000000000001338
9. Glenn, J. M., Gray, M., Wethington, L., Stone, M. B., Stewart, R., & Moyen, N. E. (2015). Acute citrulline malate supplementation improves upper- and lower-body submaximal weightlifting exercise performance in resistance-trained females. European Journal of Nutrition, 56(2), 775–784. https://doi.org/10.1007/s00394-015-1124-6
10. Wax, B., Kavazis, A. N., Weldon, K., & Sperlak, J. (2015). Effects of Supplemental Citrulline Malate Ingestion During Repeated Bouts of Lower-Body Exercise in Advanced Weightlifters. Journal of Strength and Conditioning Research, 29(3), 786–792. https://doi.org/10.1519/jsc.0000000000000670
11. Romero, M. J., Platt, D. E., & Caldwell, R. B. (2006). Therapeutic Use of Citrulline in Cardiovascular Disease. Cardiovascular Drug Reviews, 24(3–4), 275–290. https://doi.org/10.1111/j.1527-3466.2006.00275.x
12. WebMD Editorial Contributors. (2020, November 11). Health Benefits of Citrulline. WebMD. https://www.webmd.com/diet/health-benefits-citrulline