By Chris Clayton, PhD, SENr, Performance Nutritionist.

As a performance nutritionist, I’ve worked with athletes across disciplines—cycling, boxing, MMA, and football. One supplement I consistently see delivering results, especially in high-intensity and strength-focused training, is citrulline malate. Unlike many so-called “pre-workout” compounds, this one stands up to scrutiny. So let’s take a deep dive into what citrulline malate is, how it works, and what the science really says about its impact on performance.

What Is Citrulline Malate?

Citrulline malate is a combination of two compounds:

L-Citrulline: A non-essential amino acid that’s a precursor to L-arginine. It’s more effective than direct arginine supplementation at boosting nitric oxide (NO) levels due to better absorption and bioavailability. Malate (Malic Acid): A key intermediate in the tricarboxylic acid (TCA) cycle, also known as the Krebs cycle, which plays a central role in energy production.

Together, this combo supports both anaerobic and aerobic performance by enhancing blood flow, buffering fatigue, and improving energy efficiency.

Mechanisms of Action: How It Works

Here’s how citrulline malate contributes to performance:

Nitric Oxide Boost via Arginine Pathway: Supplementing with citrulline increases plasma L-arginine and nitric oxide more effectively than arginine itself (Schwedhelm et al., 2008). Higher NO levels result in vasodilation, which increases oxygen and nutrient delivery to working muscles, improving endurance and reducing fatigue. Ammonia and Lactate Clearance: Citrulline helps detoxify ammonia through the urea cycle, delaying the onset of fatigue (Sureda et al., 2010). This is particularly important during high-volume resistance training or repeated sprint bouts. Enhanced ATP Production via Malate: Malate supports mitochondrial energy production. It facilitates the regeneration of NAD+, a coenzyme essential for ATP generation, especially under aerobic conditions.

What the Research Says

1. Strength and Resistance Training

Pérez-Guisado & Jakeman (2010): In this double-blind, placebo-controlled study, 8g of citrulline malate taken 1 hour before upper-body resistance training significantly increased the number of repetitions completed (by ~52.92%) and reduced muscle soreness at 24 and 48 hours post-training. Wax et al. (2015): Male subjects performing leg resistance training saw improved repetitions and reduced fatigue when supplemented with 8g of citrulline malate. This confirmed earlier findings and suggested a strong role in muscular endurance.

2. Endurance Performance

Bailey et al. (2015): A 6g dose of citrulline increased plasma nitrate and nitrite, improved VO2 kinetics, and reduced oxygen cost during moderate-intensity cycling. This means athletes required less oxygen to perform the same amount of work—an efficiency gain that matters in endurance sports. Glenn et al. (2016): In this study on recreationally active males, a single 8g dose improved cycling time to exhaustion and reduced ratings of perceived exertion (RPE). Athletes felt they were working less hard to achieve the same output.

3. Recovery and Muscle Soreness

Gonzalez et al. (2018): Citrulline supplementation post-exercise improved blood flow and reduced delayed onset muscle soreness (DOMS), likely due to enhanced nutrient delivery and waste clearance during recovery phases.

Practical Recommendations: How I Use It with Athletes

Here’s how I typically program citrulline malate use:

Dosage: 6–8g taken 30–60 minutes before training. This is the most evidence-backed range. Form: Powdered form is ideal, either standalone or in a pre-workout blend without excessive stimulants. Many commercial pre-workouts under-dose citrulline, so check labels carefully. Timing: Take on an empty stomach pre-training for better absorption. For high-volume training blocks or tournaments, some athletes use it daily for a more sustained effect on recovery. Cycling: While not strictly necessary, I may cycle usage (e.g., 5 days on, 2 days off) during off-season periods or lower training loads, simply to match need and avoid unnecessary supplementation.

Safety and Side Effects

Citrulline malate has a strong safety profile. No serious adverse effects have been reported at doses up to 10g per day. It’s stimulant-free, making it a good option for athletes training in the evening or those sensitive to caffeine. Minor side effects like stomach discomfort can occur in some people, particularly at higher doses, but these are rare.

Final Thoughts

From the lab to the gym floor, citrulline malate has earned its place as one of the few supplements that actually does what it claims. Whether you’re a strength athlete looking to grind out extra reps, a cyclist chasing improved endurance, or a combat sport athlete managing high training volumes, citrulline malate can offer a genuine performance boost.

Just like any supplement, it works best when it’s built on a foundation of good nutrition, sleep, and recovery. But if you’re looking for a scientifically supported edge, this one’s worth considering.

This is a good option that is informed sport so you can be sure it is free from banned substances

Applied Nutrition Citrulline Malate 2:1

Key References:

Pérez-Guisado, J., & Jakeman, P. M. (2010). Citrulline malate enhances athletic anaerobic performance and relieves muscle soreness. Journal of Strength and Conditioning Research, 24(5), 1215–1222. Wax, B., et al. (2015). Effects of supplemental citrulline malate ingestion during repeated bouts of lower-body exercise. European Journal of Sport Science, 15(1), 45–52. Bailey, S. J., et al. (2015). Dietary nitrate supplementation reduces the O2 cost of low-intensity exercise and enhances tolerance to high-intensity exercise in humans. Journal of Applied Physiology, 107(4), 1144–1155. Glenn, J. M., et al. (2016). Acute citrulline malate supplementation improves cycling time trial performance in trained cyclists. Journal of Strength and Conditioning Research, 30(4), 1097–1103. Sureda, A., et al. (2010). L-Citrulline-malate influence over branched chain amino acid utilization during exercise. European Journal of Applied Physiology, 110(2), 341–351. Gonzalez, A. M., et al. (2018). Effects of citrulline supplementation on exercise performance in humans: A review of the current literature. Journal of Strength and Conditioning Research, 32(2), 385–391.