Citrulline Malate Might Make the Cut

Introduction

It’s a good thing to be able to change your mind. If you desire being ‘right’ more than being ‘correct’, congratulations you just became your own barrier to your intellectual and emotional growth. Anyway, I bring this up because in the most recent article here I wrote about supplements, I specifically discussed why Citrulline Malate (CM) didn’t make the cut for the recommended supplements in the Muscle and Strength Nutrition Pyramid. Well, since I wrote that article (originally written in August 2015) a fair bit of research has been published on CM that may make me change my mind.

To reiterate the philosophy I advise when considering whether or not to take a supplement, I believe one should wait for a preponderance of evidence to become available from multiple sources, before jumping on the band wagon. This is in opposition to the common mind set of buying anything and everything that even has the tiniest bit of evidence “just in case”, so as not to not miss out on all of the hypothetical gains. The reason I advise this philosophy is because there are actual dangers to taking supplements that are under studied beyond just pissing away your hard-earned money. I’ll paraphrase The Muscle and Strength Pyramid Nutrition Book here to illustrate my point:

“Remember D-Aspartic acid? A study came out in 2009 that found it increased testosterone production [8]. Immediately, supplement companies started selling it as a muscle builder, libido and performance enhancer. I cautioned to wait until further studies had been performed before taking it, considering this was the one and only human trial. Many ignored me, and then to their surprise (but not mine) a study came out in 2013 that found D-Aspartic acid failed not only to increase testosterone levels, but also to change body composition or strength [9]. Once again, another supplement proves to be a waste of money right? Wrong. A study recently came out that found D-Aspartic acid actually decreased testosterone levels in resistance-trained men [10]! So not only did it end up being a waste of money, it was found to be potentially counterproductive.”

So, this is why I take a relatively conservative view on supplementation and only recommend the most rigorously tested supplements that have shown clear efficacy. In fact, many who have consulted with me over the years have found that the initial cost of doing so was offset if not exceeded by the amount they saved on supplements after I advised them to let go of more than half of what they were taking.

Don’t forget the relative importance (or lack thereof) of supplementation in the grand scheme

Citrulline Malate

So as I stated in my last blog post, my main beef with CM was that the only study on resistance training that supported the use of CM was set up with a training protocol that was suboptimal in order for it to work. In the study, the participants did multiple sets of bench press, to failure, with only 1 minute of rest between sets. The mechanisms by which CM is thought to work relate to increased ATP production, efficiency of ATP usage and potentially as a buffering agent. Thus, it would be thought to improve muscular endurance, which would be more important when training in a highly fatigued state, such as was induced by the type of training done in that study (3). For those of you who have read the Muscle and Strength Training Pyramid, watched the video series, or even downloaded the sample chapter, you know this is an ineffective way to train for hypertrophy or strength and thus I couldn’t be sure that CM would be effective in a less fatigued state when training with more appropriate rest periods.

Since this was the only published study I was aware of concerning lifting performance at the time that I wrote and recorded the pyramids, I felt that CM simply didn’t make the cut as there was not a preponderance of evidence in support of its use. However, recently four studies (that I am aware of) have been published relevant to muscle and strength development on CM, from two different groups of researchers (1, 2, 4, 5). One of these studies used 80% of 1RM on the bench press and leg press for multiple sets taken to failure with just 1 minute rest between sets (2). While more total volume was performed when using CM, like the original study that I was unconvinced by (3), it suffers the same flaw of having too short a rest interval to determine if CM has a beneficial effect when training with longer rest periods such as I advise in my book. However, two of the other studies, one with participants performing chin ups, pull ups and push ups to failure (4) and another with participants performing leg presses, hack squats and leg extensions to failure with 60% 1RM (5), also reported more volume performed when using CM and in these studies a 3 minute rest interval was used. Additionally, the last of the studies in question found an increase in maximal grip strength in the group using CM (1) which is surprising given this is not a measure of muscular endurance either globally or acutely. To lend a bit more credence to these findings, it should be pointed out that all of these studies were double-blind, placebo controlled trials.

Conclusion

Based on the newest evidence from multiple sources, using double-blind placebo controlled trials on CM showing the potential benefits to total volume performed when using appropriate rest periods, and the potential that CM could positively impact maximal strength, I am inclined to shift my position that CM may in fact be a worthwhile supplement to consider as a strength or physique athlete or enthusiast. I would suspect the largest benefits would be seen during a higher volume block of training with relatively high RPE values, but it is possible that strength could be positively influenced as well. However, a single study on grip strength is not conclusive by any means and more research is needed on maximal strength using more realistic testing such as a squat or bench press or leg press 1RM. For those who have purchased the Muscle and Strength Pyramids dual set with lifetime updates, be on the lookout when we publish the first major revision for the supplementation section to be updated.

References

1. Glenn JM, Gray M, Jensen A, Stone MS, and Vincenzo JL. Acute citrulline-malate supplementation improves maximal strength and anaerobic power in female, masters athletes tennis players. Eur J Sport Sci: 1-9, 2016.
2. Glenn JM, Gray M, Wethington LN, Stone MS, Stewart RW, Jr., and Moyen NE. Acute citrulline malate supplementation improves upper- and lower-body submaximal weightlifting exercise performance in resistance-trained females. Eur J Nutr, 2015.
3. Perez-Guisado J and Jakeman PM. Citrulline malate enhances athletic anaerobic performance and relieves muscle soreness. J Strength Cond Res 24: 1215-1222, 2010.
4. Wax B, Kavazis AN, and Luckett W. Effects of Supplemental Citrulline-Malate Ingestion on Blood Lactate, Cardiovascular Dynamics, and Resistance Exercise Performance in Trained Males. Journal of dietary supplements 13: 269-282, 2016.
5. Wax B, Kavazis AN, Weldon K, and Sperlak J. Effects of supplemental citrulline malate ingestion during repeated bouts of lower-body exercise in advanced weightlifters. J Strength Cond Res 29: 786-792, 2015.