Nitric oxide supplements are widely used in sports nutrition to support muscle pumps, circulation, and workout performance. Often referred to as pump supplements or non-stim pre-workouts, these formulas are designed to enhance blood flow without relying on stimulants like caffeine.
What Is Nitric Oxide?
Nitric oxide is a naturally produced signaling molecule in the body that plays an important role in vasodilation, or the widening of blood vessels. When blood vessels relax and widen, circulation improves, allowing more oxygen and nutrients to reach working muscles during exercise.1
The body can support nitric oxide production through two major pathways:
- L-arginine pathway: Arginine is converted into nitric oxide through nitric oxide synthase enzymes1
- Nitrate pathway: Dietary nitrates, such as those found in beetroot, are converted into nitrite and then nitric oxide2
How Nitric Oxide Supports Muscle Pumps
The muscle “pump” many gym-goers experience during training is largely driven by increased blood flow to active muscle tissue. Nitric oxide boosters are used to help support this process by encouraging circulation and vascular function.
This may help contribute to:
- Greater muscle fullness during training
- Enhanced vascularity
- Improved delivery of oxygen and nutrients to muscles
- Better overall training performance and endurance
Some research suggests that nitric oxide–supporting ingredients may help improve exercise efficiency and reduce fatigue during intense workouts.3
Why Many Pump Products Are Called Non-Stim Pre-Workouts
Many nitric oxide supplements are commonly used as non-stim pre-workouts because they are taken before training to support performance, but they do not rely on caffeine or other stimulants. Instead, they focus on blood flow, hydration, and muscular performance.
This makes them a popular option for:
- Evening workouts
- People sensitive to caffeine
- Anyone who wants better pumps without stimulant effects
- Users who want to stack a pump product with a stimulant pre-workout
If you want to learn which ingredients matter most, see our guide on best ingredients for muscle pumps.
Key Ingredients That Support Nitric Oxide
- L-Citrulline: Helps increase arginine levels and nitric oxide production4
- Citrulline Malate: Often used for pump support and may help reduce exercise fatigue5
- Beetroot Extract: Provides dietary nitrates that support nitric oxide production through the nitrate pathway2
- Arginine: A direct nitric oxide precursor, though it may be less effective orally than citrulline4
- Glycerol: Supports hydration and muscle fullness during workouts6
Many of these formulas are also used as stim vs non-stim pre-workouts, depending on whether they contain caffeine.
For more practical strategies, read our guide on how to maximize muscle pumps without stimulants.
Bottom Line
Nitric oxide supplements are a popular category of stim-free pre-workouts that support circulation, pumps, and workout performance. They are especially useful for athletes who want a stimulant-free option or who want to combine pump support with other pre-workout ingredients.
Shop Nitric Oxide and Muscle Pump Supplements →
References
- Moncada S, Higgs A. The L-arginine-nitric oxide pathway. N Engl J Med.
- Lundberg JO, Weitzberg E, Gladwin MT. The nitrate-nitrite-nitric oxide pathway. Nat Rev Drug Discov.
- Domínguez R, et al. Effects of nitric oxide supplementation on exercise performance. Sports Med.
- Schwedhelm E, et al. Oral L-citrulline increases plasma arginine levels. Br J Clin Pharmacol.
- Pérez-Guisado J, Jakeman PM. Citrulline malate and resistance exercise performance. J Strength Cond Res.
- Goulet EDB. Glycerol-induced hyperhydration and endurance performance. Sports Med.