In recent times, citrulline has become one of the health industry’s more popular supplements due to its effect on athletic performance. Citrulline appeals to athletes because it helps delay the onset of muscle fatigue during intense exercise.
As such, citrulline has become a staple ingredient for many athletes and gym-goers looking to boost their endurance and increase their time to exhaustion.
10 Potential Benefits of Citrulline Malate
- Increases Vascularity
- Improves Endurance
- Aids Muscle Recovery
- Aids Muscle Growth
- Aids Protein Synthesis
- Reduces Exercise Fatigue
- Boosts Nitric Oxide Levels
- Encourages Muscle Pumps
- Improves Blood Circulation
- Normalizes Blood Pressure
You can find citrulline in fruits and vegetables like gourds, bitter melons, cucumbers, pumpkins, and watermelons. As a nonessential amino acid, your body can produce citrulline, and you don’t need to get citrulline from your diet. However, you can get additional citrulline from food, or take dietary supplements to increase the amount of citrulline in your body.
According to studies conducted by Florida State University and Marymount University, citrulline plays a role in building muscles, widening blood vessels, and reducing muscle fatigue. Citrulline reduces fatigue by stimulating the urea cycle into action, eliminating ammonia produced by muscles before ammonia has a chance to affect the muscles.
Citrulline is also produced when the body converts arginine into nitric oxide. Several studies show that excess citrulline causes an increase in arginine in the blood, increasing the amount of circulating nitric oxide.
When it comes to nitric oxide, more nitric oxide means better blood flow, and, therefore, better muscle pumps. Increased nitric oxide also allows more nutrients and oxygen to enter the muscles. Once you take citrulline, citrulline converts into arginine, which is then converted into nitric oxide. This increase in nitric oxide leads to vasodilation, causing blood vessels to relax.
Citrulline for Strength and Endurance
There have been several studies based around citrulline malate and its effect on athletic performance. However, it’s important to note that most endurance studies use the supplement L-citrulline, while strength studies use citrulline malate.
Despite claims to the contrary, a single dose of citrulline doesn’t appear to have any effect on endurance performance. This finding contrasts with regular citrulline doses that seem to have a positive effect on exercise performance.
One study by Texas Tech University found that regular citrulline doses increased nitric oxide synthesis, decreased blood pressure, and increased peripheral blood flow. These changes accompanied improved muscle oxygenation and performance during endurance activity.
Additionally, citrulline is said to be beneficial for athletes because it increases the oxygen content of muscles, allowing the body to work harder for longer without experiencing fatigue. While this claim is valid for working muscles, it’s not valid for oxygen used by the body as a whole, which is essential for improved performance.
A study published in the Journal of Applied Physiology found that cyclists who took L-citrulline increased their cycle peak power by 9% compared to cyclists who didn’t take L-citrulline.
The study noted that total work completed during a 60-second cycle sprint improved by 7%, and intense exercise tolerance increased by 12 percent. These findings suggest that short-term citrulline supplementation in athletes can elicit positive effects on muscle power and metabolic responses.
Citrulline malate seems to benefit muscle force production and improve muscle efficiency, although studies investigating the effects of citrulline on exercise performance and muscle fatigue are still limited and ambiguous.
Citrulline and Muscle Growth
Several studies show that L-citrulline increases nitric oxide and vascular activity, which may contribute to improved muscle growth. A report in the Journal of Strength and Conditioning Research examined the effect of citrulline malate on barbell bench press performance as a form of aerobic exercise.
The study tested the subjects’ resistance using bench press repetitions to fatigue at 80% of one-rep max over eight sets. The results of the study reported an increase in the number of repetitions for the citrulline group compared to the placebo group. This increase was positively correlated with the number of sets completed (with the citrulline group achieving 52.9% more repetitions).
There was also a 40% decrease in muscle soreness at 24 hours and 48 hours after training in the group that took citrulline malate. Another study published in Biochemical Genetics measured the effect of citrulline malate on blood lactate levels—a marker of muscular fatigue in handball players.
The handball players took 1 gram of citrulline three times per day, and blood lactate levels were measured before and after training. After the study, results showed a significant decrease in lactate levels in the subjects taking citrulline. In contrast, the placebo group did not show any reduction in lactate levels.
The results indicate that supplementing with citrulline malate may help postpone the effects of fatigue during high-intensity endurance exercise. Furthermore, a study by Mississippi State University examining 12 advanced resistance-trained men hypothesized that citrulline malate would mitigate fatigue in muscles before working out.
The results of the Mississippi University study showed that male athletes who consumed citrulline malate experienced less fatigue in working muscles than the placebo group, which allowed them to complete more repetitions on exercises. According to research, there appears to be some benefit to supplementing with citrulline malate to improve strength and muscle growth.
Types of Citrulline Supplements
There are two primary forms of citrulline:
L-Citrulline: is a by-product of the conversion of arginine into nitric oxide. Studies show that if there is excess citrulline in the body, levels of arginine increase in the blood, which, in turn, increases nitric oxide production.
The more nitric oxide there is in your body, the more blood flows to your muscles as you exercise. This increased blood flow should, in theory, permit your muscles to work for longer without fatigue.
Citrulline Malate: is a combination of citrulline and malate, a compound that’s essential for the production of energy. You may be wondering what the malate in citrulline malate stands for and why it’s useful?
In nature, malate causes the sour flavor in apples and other fruits. As a supplement, malate binds to citrulline to make citrulline more stable within the body. These two kinds of supplements lead to similar effects, but when it comes to sports supplements, citrulline malate is more popular. In supplement research, however, it isn’t easy to determine which effects are due to citrulline and which effects are due to malate.
During the original creation of pre-workout supplements, manufacturers often filled pre-workout supplements with L-arginine, as many researchers believed that more arginine led to faster recovery and better protein synthesis in the muscles.
In recent years, however, there’s been a shift away from arginine towards citrulline. This shift occurred because citrulline is, counter-intuitively, more effective than arginine at increasing arginine levels.
A German study discovered that 3 grams of citrulline malate provides the same vascular benefits as 6 grams of arginine in heart patients. On top of this, citrulline isn’t broken down by the liver as fast as arginine, so the benefits of citrulline last much longer. As a result, bodybuilders and athletes can get the vascular benefits of arginine with fewer side effects by taking citrulline malate.
Safety and Side Effects
Compared to other supplements, there’s little information available on the safety of citrulline. One study published in the British Journal of Nutrition examined the effect of citrulline on men who consumed 2 grams, 5 grams, 10 grams, and 15 grams of citrulline on separate occasions.
Results showed that even at the highest citrulline dose of 15 grams, the men reported no adverse side effects (including nausea or diarrhea).
Based on current research, it’s best to take 3-6 grams of L-citrulline, which equates to 8 grams of citrulline malate.
To increase muscle oxygen capacity, 6 grams of L-citrulline for seven days appears to be effective, while research suggests that 3-6 grams of L-citrulline is effective for reducing blood pressure.
If you want to supplement with citrulline to improve athletic performance, it’s best to take citrulline malate at least an hour before working out.
Citrulline malate takes about an hour to convert into nitric oxide. Therefore, if you take citrulline more than one hour before working out, citrulline may not deliver significant benefits.
Effectiveness of Citrulline Malate
Citrulline supplementation boosts arginine and nitric oxide levels, although citrulline’s effect on exercise performance remains limited. Many studies on resistance-trained individuals report that taking citrulline before working out can benefit weightlifting performance and reduce muscle soreness, but citrulline appears to offer no benefits for untrained adults.
Furthermore, long-term supplementation with either L-citrulline or citrulline malate shows no improvement in body composition or muscle strength.
With that said, citrulline supplementation does show some benefit and appears to be safe for consumption with no known side effects. However, citrulline may prove more beneficial for improving the health of blood vessels and lowering blood pressure than improving overall exercise performance.
If you’re a hardcore athlete looking to get an edge in competition, supplementing with 5, 10, or 15 grams of citrulline might improve your performance and decrease fatigue during exercise. If, on the other hand, you’re an occasional gym-goer who hits the weights only every so often, supplementing with citrulline will be of little benefit.