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.
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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
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