What is the Main Ingredient in Pump Supplements?

October 26, 2025 •

4 min read

According to a 2020 review, L-citrulline supplementation can reduce muscle soreness and increase nitric oxide synthesis, making it a key element in achieving the sought-after 'pump'. This article will delve into what is the main ingredient in pump supplements, its function, and other vital ingredients for maximizing performance.

Quick Summary

The main ingredient in pump supplements is typically L-citrulline, or its variant L-citrulline malate, due to its effectiveness in promoting nitric oxide production. This leads to vasodilation, increasing blood flow to muscles and resulting in the temporary feeling of fullness and vascularity known as the muscle pump. Other ingredients like beetroot extract and glycerol also contribute to this effect.

Key Points

L-Citrulline is Primary: The amino acid L-citrulline is the most prominent and effective ingredient for promoting muscle pumps by boosting nitric oxide production.
Nitric Oxide is Key: The muscle pump is caused by vasodilation, the widening of blood vessels due to increased nitric oxide (NO), which improves blood flow to muscles.
Beetroot is a Natural Alternative: Beetroot extract is a rich source of nitrates that naturally increase nitric oxide levels and enhance athletic performance.
Arginine is Less Effective Orally: Direct oral L-arginine supplementation is less efficient for boosting nitric oxide than L-citrulline due to poor absorption and breakdown in the body.
Hydration Boosts the Pump: Ingredients like glycerol monostearate increase hydration within muscle cells, contributing to the feeling of fullness and vascularity.
Combine for a Better Effect: Many supplements combine L-citrulline with other ingredients like beetroot and Nitrosigine for a synergistic and more potent pump.
Training Technique Matters: High-volume, moderate-rep training with short rest periods is essential to create the metabolic stress necessary for a strong muscle pump.

The Science Behind the Muscle Pump

The muscle pump is a temporary increase in muscle size caused by an influx of blood and fluids during exercise. This phenomenon, also known as transient hypertrophy, is driven by an increase in nitric oxide (NO) production, which acts as a vasodilator to relax and widen blood vessels. The subsequent increase in blood flow delivers more oxygen and nutrients to the working muscles and removes waste products, which can help delay fatigue. By understanding the ingredients that promote this effect, athletes can select supplements to maximize their training sessions.

Why L-Citrulline Is the Primary Ingredient

L-citrulline is consistently identified as the key ingredient in pump supplements due to its superior ability to raise blood arginine levels, a direct precursor to nitric oxide. Unlike supplementing with L-arginine directly, which has poor oral bioavailability and can cause gastrointestinal issues, L-citrulline is absorbed more efficiently and is converted to L-arginine in the kidneys. This makes it a far more effective and reliable method for increasing NO production and achieving a significant muscle pump. Research has shown that dosages of 6-8 grams of L-citrulline are effective for enhancing athletic anaerobic performance and reducing muscle soreness. The malate version, L-citrulline malate, combines citrulline with malic acid, which some studies suggest may have additional benefits for energy production, though the debate continues on which form is superior.

Other Powerful Pump-Enhancing Ingredients

While L-citrulline is the star, several other ingredients work synergistically to improve muscle pump. For example, beetroot extract is a potent natural source of dietary nitrates. Once consumed, these nitrates are converted into nitric oxide, further promoting vasodilation and increased blood flow to the muscles. Glycerol monostearate is another popular addition. This compound is known for its ability to draw and hold water within muscle cells, a state known as hyperhydration. This creates a fuller, more engorged muscle appearance and helps prevent dehydration during intense workouts.

Other notable ingredients include the following:

Nitrosigine: A patented compound of arginine silicate inositol shown to be highly effective at increasing nitric oxide levels and blood flow, with some studies suggesting it is equally effective at a much lower dose than citrulline malate.
Agmatine Sulfate: A metabolite of arginine that helps modulate nitric oxide synthase, the enzyme that produces NO.
Betaine Anhydrous: Helps pull water into muscle cells, boosting hydration, fullness, and cellular volume for better pumps.

Comparison of Key Pump Ingredients


Ingredient	Mechanism of Action	Typical Effective Dose	Notes
L-Citrulline	Converted to arginine in the kidneys to increase nitric oxide (NO) synthesis, causing vasodilation.	6-8 grams	More effectively raises arginine levels than supplementing with L-arginine directly.
Beetroot Extract	High in natural nitrates, which convert to nitric oxide in the body, promoting vasodilation.	3-6 grams of powder	Can improve athletic performance and endurance, particularly in endurance training.
Glycerol Monostearate	Draws water into muscle cells, increasing cellular hydration and causing muscle cell swelling.	5 grams	Requires drinking plenty of water to be effective.
Nitrosigine	A patented complex that increases nitric oxide production and blood flow, with studies showing efficacy at lower doses.	1.5 grams	Non-stimulant, and may also improve focus.
Agmatine Sulfate	Modulates nitric oxide synthase, which aids in boosting NO production.	500 mg to 2.5 grams	May also help with pain tolerance.

Synergistic Effects and Pumping Training

For an even more intense muscle pump, many manufacturers combine several of these ingredients. Combining L-citrulline with a natural nitrate source like beetroot extract can provide a powerful, multi-pronged approach to increasing nitric oxide and vasodilation. Additionally, some formulas include hydration agents like glycerol or betaine to maximize cellular swelling, further enhancing the pump effect. For example, the Patented Setria® Performance Blend uses a combination of L-citrulline and glutathione to provide a sustained nitric oxide boost.

Supplementation, however, is only one part of the equation. Achieving a significant pump also depends on proper training techniques. High-volume, moderate- to high-rep strength training with short rest periods is most effective for causing the blood and fluid to rush into the working muscle, which drives the pump response. Consistent training, proper hydration, adequate sleep, and a diet rich in carbohydrates also contribute to maximizing the pump effect and, in turn, can contribute to long-term muscle growth.

Conclusion

The main ingredient in most pump supplements is L-citrulline, prized for its ability to effectively raise the body's nitric oxide levels and drive powerful vasodilation. This leads to the characteristic feeling of muscle fullness and increased vascularity during and after a workout, which is a temporary state known as transient hypertrophy. While L-citrulline is the star player, other ingredients like beetroot extract, glycerol monostearate, and Nitrosigine all contribute to this effect through various mechanisms, including enhancing nitric oxide production, improving blood flow, and increasing cellular hydration. The most effective pump supplements often combine these ingredients to create a synergistic effect, maximizing the influx of oxygen, blood, and nutrients to the muscles during training. When paired with high-volume training, proper hydration, and a balanced diet, these supplements can help elevate workout performance and enhance the satisfying physical and psychological aspects of achieving a great muscle pump.

Visit the NIH website for more information on the efficacy of L-citrulline

Frequently Asked Questions

L-citrulline is an amino acid that converts to arginine to produce nitric oxide. L-citrulline malate is a combination of L-citrulline with malic acid, an organic salt. Some believe malic acid offers additional energy-boosting benefits, but research on the superiority of one form over the other is mixed.

L-citrulline has a significantly better absorption rate than L-arginine. When you ingest L-citrulline, your kidneys convert it into L-arginine, leading to higher and more consistent blood arginine levels, and thus greater nitric oxide production. Directly supplementing with L-arginine often results in poor absorption and potential gastrointestinal side effects at high doses.

Beetroot is naturally rich in dietary nitrates. When you consume it, your body converts these nitrates into nitric oxide. This process works alongside L-citrulline to promote vasodilation, widening blood vessels and increasing blood flow to the muscles.

Glycerol monostearate is a hygroscopic compound, meaning it draws water into the muscle cells. This super-hydrates the muscles, causing cell swelling that contributes to the 'full' and engorged feeling of a pump. It also helps combat dehydration during intense workouts.

Yes, it is possible to achieve a pump naturally through high-volume training with moderate weights and short rest periods. Proper hydration and a diet rich in nitrates (found in foods like spinach and beets) can also contribute to this effect. Supplements can enhance the process, but they are not the only way to get a pump.

A muscle pump is a temporary state, typically lasting anywhere from 2 to 3 hours after a workout. However, its duration can vary based on the intensity of your training, your hydration levels, and the supplements you have consumed.

Nitrosigine is a patented complex of arginine silicate inositol. It is designed to boost nitric oxide levels and blood flow more effectively and consistently than traditional L-arginine, with some studies showing it to be as effective as a much higher dose of citrulline malate.