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L-Citrulline vs. Citrulline Malate for Muscle Building

by Trevor Hiltbrand | Reviewed by Advisory Board

l citrulline vs citrulline malate

If your goal is to build muscle, chances are your on the lookout for new hacks to improve training performance, muscle growth and recovery. One of the most efficient ways to improve each of these categories is to boost nitric oxide production in the body.

Nitric oxide offers a myriad of benefits to any gym-goer, but most importantly, increasing nitric oxide creates more vasodilation, which allows for more blood flow, oxygen and nutrients to be transported to the muscles.

As a result a lifter may experience greater stamina, endurance and be blessed with the famous “pump” that Arnold Schwarzenegger often references in interviews and the documentary, Pumping Iron. Long-term results of increased nitric oxide production include faster muscle recovery between training sessions and enhanced muscle growth. Those are benefits that no lifter would ever purposely ignore.


What is L-Citrulline and How Does it Affect Nitric Oxide?

l citrulline

L-Citrulline has become something of a “buzz word” in the fitness community during the last few years. A key ingredient in many pre-workout formulas, L-Citrulline is a non-proteinogenic amino acid that may help reduce fatigue associated with high intensity training, and plays a key role in the urea cycle, the process that is responsible for removing metabolic waste generated from exercise. But how are L-Citrulline and nitric oxide correlated?

When L-Citrulline is consumed, the kidneys convert it to arginine, which the body immediately uses to generate nitric oxide. The higher the arginine levels are in your body, the greater your nitric oxide output will be. If you recall what we said just a second ago about nitric oxide, you’ll know that having more nitric oxide will lead to greater muscle growth over time.

Is L-Citrulline Beneficial as a Supplement?

people choosing supplements in store

L-Citrulline can be obtained naturally through a variety of fruits, like watermelon. But as with most other amino acids, it is not feasible to get a sufficient amount of L-Citrulline from food alone, which is why supplementation makes sense.

There have been a few studies conducted on L-Citrulline supplementation and its impact on exercise performance, but surprisingly, most of the studies have been somewhat inconclusive.

One study consisted of seventeen young (18-34 year old) healthy male and female volunteers that participated in incremental treadmill tests to exhaustion following placebo or L-Citrulline ingestion. Each participant was given 3 grams of L-Citrulline or the placebo 3 hours before the test, or 9 grams over 24 hours after completing the test. The purpose of the study was to determine if the time to exhaustion could be improved in the study participants who received L-Citrulline compared to the placebo.

Based on everything we just highlighted about L-Citrulline, you’d think there would be a marked difference between the exercise performance of the placebo group and the group that actually ingested L-Citrulline during the pre-workout or post-workout period. Interestingly enough, that was not the case.

The results of the study show that the treadmill time to exhaustion was actually lower following citrulline ingestion than during the placebo trials, which contradicted the original hypothesis created before the study commenced.

What About L-Citrulline vs. Citrulline Malate?

citrulline malate

There are a lot of fitness experts out there that believe L-Citrulline does more for performance than Citrulline Malate because it is a pure amino acid, but the research suggests otherwise. Up until this point, there have not been any human studies that compare L-Citrulline to Citrulline Malate head-to-head.

Some experts suggest that L-Citrulline may be more beneficial for individuals who are trying to improve their endurance (aerobic) exercise performance. But once again, the research is unclear on this statement as well.

As with the last study we referenced, it is very unclear whether L-Citrulline offers a significant improvement in exercise performance compared to those who do not supplement with it. Some studies even point out a decrease in performance, like the study we mentioned earlier.

However, Citrulline Malate tells a slightly different story. But what is Citrulline Malate?

Citrulline Malate is an organic compound that naturally occurs in many fruits, namely apples. Traditionally, malic acid is used as a preservative in packaged foods to prevent spoilage, but it has also been documented that if taken as a supplement, it can improve stamina and reduce the pain and inflammation induced by high intensity training.

The biggest difference between pure L-Citrulline and Citrulline Malate is the role Citrulline Malate plays in the Krebs cycle or TCA cycle. In this process, Citrulline Malate converts the food we ingest into useable energy, specifically ATP, which helps provide more energy for high intensity exercise. Because Citrulline Malate has been shown to enhance aerobic and anaerobic energy production and carries with it the benefits of L-Citrulline (increasing nitric oxide), it offers a perfect one-two punch for anyone looking to maximize recovery and muscle growth.

Citrulline Malate Study #1

Unlike L-Citrulline, the effectiveness of Citrulline Malate is backed by several research studies.

One such study was conducted in 6 different gyms in the South of Spain. During the study, the participants were tested on their 1 repetition maximum for the flat barbell bench press. Before engaging in the bench press strength test, participants consumed (8 g) of Citrulline Malate or placebo (2-period crossover design) 1 hour before the workout. The participants completed 8 sets of bench press at 80% of their 1 rep maximum to complete muscle fatigue during the course of a chest-focused workout (4 sets at the beginning of the workout and 4 sets near the conclusion of the workout). The participants continued a series of 5 workouts per week for 2 weeks (chest, back, legs, shoulders, arms).

The results of the study showed a strong correlation between the ingestion of Citrulline Malate and an increase in the number of repetitions completed in the bench press test by the majority of study participants. These results led the researchers to believe that Citrulline Malate may help individuals lift more weight and more repetitions in the gym during each training session, while also recovering more quickly after each session.

Citrulline Malate Study #2

In another study conducted on the potential benefits of Citrulline Malate, a group of handball players were evaluated to see if Citrulline Malate could help decrease blood lactate level and postpone exercise fatigue.

For a period of 4 weeks, the handball players engaged in high intensity training for 4 days per week. The training primarily consisted of strength/resistance training and technique training for their sport. The athletes were given Stimol (contains Citrulline Malate) 3 times per day. They were given a 1 gram dose in the morning for breakfast, 1 gram during midday for lunch, and 1 gram in the evening for dinner. The placebo group was only given the placebo during these same periods during the day. The blood lactate levels of the athletes were measured before the training program began and after it concluded.

The results of the study showed a significant decrease in blood lactate levels immediately after exercise for those participants taking the Stimol supplement. The placebo group did not show any significant decrease in blood lactate levels during the study. The results give a lot of evidence that supplementing with Citrulline Malate may help postpone the effects of fatigue while participating in high intensity or endurance exercise.

What is the end Verdict on L-Citrulline vs. Citrulline Malate?

While there is not much positive research support for L-Citrulline when it comes to exercise performance, the research for Citrulline Malate suggests that it can help postpone exercise fatigue, improve recovery and increase nitric oxide production in the body, which will help increase blood flow and enhance muscle growth over time.

If you’re looking for a performance edge in the gym, citrulline malate may be a great option. When you compare L-Citrulline vs. Citrulline Malate, Citrulline Malate is the clear winner. At Transparent Labs, we offer Citrulline Malate as a stand alone, or you can get a healthy dose of Citrulline Malate in our legendary pre-workout formulas. If you want to crush it in the gym and make the gains you’re hoping for in the coming year, give Citrulline Malate a test run and see what happens.

Trevor Hiltbrand
Trevor Hiltbrand


Trevor Hiltbrand is one of the owners/co-founders of Transparent Labs and head of content creation. He got his start with supplement research back in 2013 when he began researching cognitive enhancement. With the help of the Transparent Labs Expert Panel and Advisory Board, we aim to bring our evidence based nutrition and exercise research to the world.

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