After posting the interview with Complete Strength's Rob Whitfield, I got a message showing interest in Complete Strength PreV2. They asked me why do they use straight l-citrulline though instead of citrulline malate. So I thought I'd answer it here. A lot of the research where the claims come from use citrulline malate, however when you read the full papers and then cross reference them with research using pure citrulline, it becomes obvious that the benefits come from citrulline itself.
You see, citrulline malate is a bond of the amino acid citrulline and malic acid. If its listed as 2:1 on the label, then it is two parts citrulline to one part malic acid. If it doesn't declare this, then you are getting the inferior 1:1, 50% citrulline and 50% malic acid. Don't get me wrong, malic acid has its benefits too but we are taking this ingredient for muscle pump and endurance, so it is the citrulline we are truly after. Because out of the two ingredients citrulline is the pricier one (due to the dosage needed), many brands cheap out and use a 1:1.
Now, lets see how citrulline works and why you want it. As I mentioned above, citrulline is an amino acid and is used for muscular pump. It is one of three involved in the urea cycle, alongside arginine and ornithine. The urea cycle was discovered by Hans Krebs (who also discovered Krebs cycle) and his associate Kurt Henseleit in 1932.
In the human body, deamination is used to break down amino acids for energy. The amino group is removed from the amino acid molecule and converted to ammonia. This frees up the carbon and hydrogen groups of the amino acid and is either recycled or oxidized for energy.
Ammonia production is greatest during prolonged exercise due to the main fuels for sustaining moderate to high intensity exercise being carbohydrates and fats. The most efficient means of converting these macronutrients into ATP is via the Krebs cycle and oxidative phosphorylation. The more intense the exercise the greater the ammonia created.
Ammonia is toxic in high levels, so the liver converts ammonia to urea (a less toxic substance through a series of reactions known as the urea cycle. The urea then travels through the bloodstream to the kidneys and is excreted in the urine.
Since l-ornithine is synthesized into citrulline by reacting with carbamoyl phosphate in the presence of ornithine transcarbamoylase, and arginosuccinate is synthesized from citrulline in presence of arginiosuccinate synthetase, that then provides arginine. So there is no need to supplement with arginine and ornithine.
Another reason to not supplement with arginine is because it simply doesn't work. The reason arginine doesn't work for increasing nitric oxide is because it has a short half life caused by arginase, which breaks it down. Citrulline however doesn't break down in the liver and intestinal tract by arginase, which is why it works.
This is evident in a study that supplemented 6 grams of citrulline malate (4 grams of which was citrulline). They noted a 173% increase in plasma citrulline, 152% increase in ornithine, and a 123% increase in arginine. The same 4g citrulline dosing was used in another study with similar result.
This makes citrulline a great ammonia buffer. By buffering ammonia citrulline reduces muscle fatigue and prevents the accumulation of ammonia. This is one way citrulline enhances athletic anaerobic performance and reduces muscle soreness.
Citrulline has shown to help the muscle better utilise amino acids as energy, further helping endurance. The same study also showed evidence of citrulline promoting creatine creation from muscle cells.
Another way citrulline works (besides increasing plasma arginine and ornithine levels) is to increase plasma nitrate levels. Nitrates are precursor to nitric oxide (NO) and potentiate NO levels by increasing the activity of NOS, the enzyme that makes NO from arginine.
As an added bonus 4 grams of citrulline has shown to raise hGH by 66.8% when measured immediately after exercise. That's quite a boost in natural growth hormone!
So how much to take? You want between 4-6g preworkout. I wouldn't recommend more as it can cause stomach issues. In Complete Strength PreV2 you get a solid 5g, which I find gives a great effect. Give Complete Strength PreV2 a try today.