Citrulline malate: Does it work?

Citrulline malate is being promoted as a way to boost endurance and give you more energy to train harder and recover faster.

Citrulline malate

Citrulline malate is a mixture of citrulline, which is involved in the urea cycle, and malate, a tricarboxylic acid cycle intermediate. It is usually prescribed as an antiasthenic treatment.

Previous studies in humans and rats show that citrulline malate improves muscle performance of subjects suffering from asthenia (a condition which describes the loss or lack of body strength).

There are very few studies on citrulline malate. Most of them involve rats. In one such study, resistance to fatigue improved after treatment with citrulline malate [2].

In one of the few human studies, researchers examined the effects of supplementation with six grams of citrulline malate daily for 15 days [1].

The results show that citrulline malate led to a significant reduction in the sensation of fatigue, a 34% increase in the rate of oxidative ATP production during exercise, and a 20% increase in the rate of phosphocreatine recovery after exercise. This indicates a larger contribution of oxidative ATP synthesis to energy production.

These results are interesting, but the study does have various weaknesses.

Firstly, the study was not double-blinded with a placebo and control group.

Studies involving food supplements, sports drinks, energy bars and other performance aids usually follow this format. A placebo is a "fake" supplement used to reduce the influence of faith and belief in a treatment on the results of a study.

Double-blinded means that neither the researcher nor the test subject knows which supplement or drug they are getting. If either person knows, it can have a big influence on the results.

"The absence of a placebo control group meant that we could not eliminate a placebo effect," say the researchers, "which would have to be addressed by a double blinded placebo versus control trial."

The exercise test used to measure performance involved finger flexions performed at 1.5 second intervals with a six-kilogram (12 pounds) weight. We don't know if the same improvements in performance would be seen during exercises such as the squat or bench press.

What's more, the subjects were 18 inactive men who complained of fatigue. They weren't regular exercisers.

In other words, the subjects were tired, inactive men who performed finger exercises before and after supplementation. Because of this, the results don't neccesarily apply to active people wanting to lose fat and build muscle.

The bottom line is that citrulline malate does have the potential to enhance performance, but more relevant human research is needed before we can conclude that it enhances strength, muscle growth or fat loss.

Related Articles

• Belly Fat and How to Beat It
• How to Fight Fat and Win (Members Only)
• The Maximum Muscle Plan (Members Only)
• The Myth about Muscle and Your Metabolic Rate

Reference
1. Bendahan, D., Mattei, J.P., Ghattas, B., Confort-Gouny, S., Le Guern, M.E., & Cozzone, P.J. (2002). Citrulline/malate promotes aerobic energy production in human exercising muscle. British Journal of Sports Medicine, 36, 282-289
2. Goubel F, Vanhoutte C, Allaf O, Verleye M, Gillardin JM. (1997). Citrulline malate limits increase in muscle fatigue induced by bacterial endotoxins. Canadian Journal of Physiology and Pharmacology, 75, 205-207
http://www.manb2p.com/findings.html