Best Nitric Oxide Supplements for Endurance Performance

Last updated: April 22, 2026

Key Takeaways

• L-Citrulline supports nitric oxide production more effectively than L-arginine because it absorbs well and converts steadily in the kidneys.¹
• Research shows cyclists can gain 12% longer time-to-exhaustion and 53% more reps with reduced soreness from 6-8g citrulline malate.¹
• Standout options include Bucked Up pre-workout with 6g citrulline malate, pure L-citrulline powder, and advanced stacks like Mother Bucker.
• Effective dosing: 6-8g pre-event for sprints and marathons, 3-6g daily for ultras, taken 30-90 minutes before training or racing.¹
• L-Citrulline is generally safe with minimal side effects; get Bucked Up’s pure L-Citrulline to support endurance and push through performance plateaus.¹

How Nitric Oxide Supports Endurance Performance

Nitric oxide acts as a key signaling molecule that widens blood vessels, which improves oxygen and nutrient delivery to working muscles during endurance efforts.¹ The L-citrulline pathway offers clear advantages over direct L-arginine supplementation because it bypasses heavy liver metabolism and provides gradual, sustained L-arginine release through kidney conversion.¹

Research demonstrates meaningful endurance benefits from effective nitric oxide support.¹ Cyclists supplementing with L-citrulline achieved longer time-to-exhaustion compared to placebo, while resistance training studies using 8g citrulline malate showed significantly more repetitions and reduced delayed onset muscle soreness.¹

The mechanism extends beyond simple vasodilation. L-citrulline participates in ammonia detoxification through the urea cycle, which helps buffer exercise-induced fatigue.¹ A 2023 meta-analysis confirmed L-citrulline’s role in reducing exercise-related ammonia accumulation, and this reduction directly influences central fatigue during prolonged endurance activities.¹

Given these performance benefits, choosing an L-citrulline supplement works best when you look at dose, ingredient combinations, and how long the effects last.¹ The products below highlight different ways endurance athletes can support nitric oxide production across a range of training and race demands.

Top 5 Nitric Oxide Supplements for Endurance in 2026

1. Bucked Up Pre-Workout: 6g Citrulline Malate for Daily Endurance Training

Bucked Up pre-workout provides full ingredient disclosure and scientifically supported dosing. The foundational Bucked Up pre-workout delivers 6g of citrulline malate in a 2:1 ratio, where the malate component supports the Krebs cycle and ATP production alongside nitric oxide benefits.¹ The formula also includes Astragin, which supports nutrient absorption and helps address citrulline uptake.¹

This profile suits athletes who want a consistent pre-workout routine that supports both endurance and power sessions.¹ The 6g citrulline malate dose aligns with research-backed ranges for performance and recovery support.¹

2. Mother Bucker: Multi-Pathway Stack for Long Sessions

Mother Bucker suits advanced athletes who want extended pump, focus, and hydration support during longer training blocks.¹ The formula combines 4g pure L-citrulline with Nitrosigine and Hydroprime glycerol to create a multi-pathway approach to performance.

By supporting arginine availability through Nitrosigine, citrulline conversion, and cellular hydration through glycerol at the same time, this stack can extend endurance benefits beyond what single-pathway nitric oxide support typically provides.¹ Athletes who train for multi-hour events or back-to-back sessions may find this style of formula especially useful.

Explore Bucked Up’s range of L-citrulline-based formulas to match your training style, from daily pre-workouts to advanced stacks.

3. Generic Pure L-Citrulline Powder

Pure L-citrulline powder works well for athletes who want simple formulas and flexible dosing. Many endurance athletes use 3-6g daily, either as a single serving or split across the day, to maintain steady nitric oxide support.¹

Bucked Up’s unflavored L-citrulline offers precise 3g scoops, which makes it easy to adjust your intake based on body weight, training volume, and event schedule. This format also stacks cleanly with other single-ingredient supplements.

4. Citrulline Malate Supplements for Combined Pump and Energy

Citrulline malate combines L-citrulline with malic acid, which may support both nitric oxide production and energy metabolism.¹ Effective doses often fall in the 6-8g range taken before exercise, with the 2:1 citrulline-to-malate ratio showing the strongest research support.

While pure L-citrulline offers maximum control over daily dosing, citrulline malate appeals to athletes who want a single ingredient that supports both endurance and perceived effort during intense sessions. Many pre-workouts, including Bucked Up, use this form for that reason.

5. Beetroot Nitrate Shots and Nitrosigine Blends

Beetroot-based supplements such as Beet-It typically provide 400-600mg of nitrates through the dietary nitrate to nitrite to nitric oxide pathway. These products often work well for short, intense events and time trials, although their effects usually last a shorter window than L-citrulline’s sustained kidney conversion.

Nitrosigine, a bonded arginine silicate, may offer improved bioavailability compared to standard L-arginine. Bucked Up includes Nitrosigine in select advanced formulas, such as Mother Bucker, where it pairs with L-citrulline to support nitric oxide through complementary mechanisms.

Supplement	Key Dose	Duration of Effect	Bucked Up Option
L-Citrulline	3-6g daily	4-6 hours	Pure L-Citrulline Powder
Citrulline Malate	6-8g pre-workout	3-4 hours	Bucked Up Pre-Workout
Beetroot Nitrates	400-600mg	2-3 hours	Not applicable
Advanced Stack	4g + synergists	6+ hours	Mother Bucker

Proven L-Citrulline Dosages and Timing for Endurance Events

Dosing works best when you match it to your experience level and event length. For running events such as 5Ks and 10Ks, many athletes use 6-8g citrulline malate taken 30-60 minutes before exercise, which reflects protocols used in performance research.¹ Cyclists often follow a similar approach, while some prefer a daily 3-6g pure L-citrulline routine to maintain steady support.

Creatine and nitric oxide precursors support different aspects of performance. Unlike creatine, which mainly helps short-burst power activities, nitric oxide precursors complement aerobic metabolism by improving oxygen utilization efficiency. Many athletes stack both, with creatine supporting ATP regeneration and L-citrulline supporting blood flow and nutrient delivery.

Event Type	Recommended Dose	Timing	Notes
5K-10K Running	6g Citrulline Malate	45 min pre-race	Focus on acute performance
Marathon/Ultra	3g Pure L-Citrulline daily	Same time each day	Supports long-term endurance
Cycling TT	6-8g Citrulline Malate	60 min pre-event	Supports power output
Triathlon	4g + synergists	90 min pre-start	Targets multiple systems

Use these protocols with Bucked Up’s clearly dosed citrulline options to align your supplement plan with your race calendar.

Safety, Side Effects, and Ideal Users for L-Citrulline

L-citrulline shows strong safety data in healthy athletes.¹ The 2023 meta-analysis of 158 participants reported no significant adverse effects from short-term supplementation¹, and a 2025 study using 10 days of supplementation at 100mg/kg daily found excellent tolerability.

Mild gastrointestinal discomfort can appear with very high single doses above 10g.¹ More relevant for endurance athletes are cardiovascular considerations. Those with naturally low blood pressure should use caution, because vasodilation can worsen hypotension. The same mechanism means athletes taking antihypertensive medications or PDE5 inhibitors should speak with a healthcare provider before starting L-citrulline.

Bucked Up products are manufactured in GMP-certified facilities, which supports consistent quality and purity for competitive athletes who follow testing protocols.

Frequently Asked Questions

Most Effective Nitric Oxide Approach for Endurance

L-citrulline offers strong bioavailability and sustained effects compared to L-arginine or beetroot nitrates.¹ The kidney conversion pathway supports longer nitric oxide elevation, which can help athletes during endurance activities that last more than 60 minutes.

L-Citrulline Dosing for Ultra-Endurance Events

For ultra-endurance events, many athletes use 3-6g of pure L-citrulline daily instead of relying only on a single pre-race dose. This pattern supports more consistent nitric oxide availability across long training cycles and extended competition periods.

How Bucked Up Compares to Other L-Citrulline Supplements

Bucked Up differentiates through published ingredient quantities, the inclusion of Astragin for absorption support, and strategic ratios such as the 2:1 citrulline malate formulation. The Mother Bucker formula adds another layer by combining multiple nitric oxide pathways with hydration support in one product.

Timing L-Citrulline Before Cycling Workouts

Take L-citrulline about 60 minutes before cycling sessions to allow time for absorption and conversion to L-arginine. This schedule lines up with peak plasma concentrations, which usually occur between 0.7 and 2 hours after ingestion, and supports nitric oxide availability during your main work intervals.

Stacking L-Citrulline with Beta-Alanine for Endurance

L-citrulline and beta-alanine work through different fatigue pathways and pair well for endurance. L-citrulline supports blood flow, oxygen delivery, and ammonia handling, while beta-alanine helps buffer acid buildup in muscles.¹ Many Bucked Up formulas include both ingredients to create broader endurance support in a single scoop.

Conclusion

L-citrulline provides reliable bioavailability and sustained nitric oxide support compared to several common alternatives used for endurance performance. Bucked Up’s evidence-based formulations give athletes clear ingredient amounts and combinations that align with current research.

Some athletes may prefer the straightforward 6g citrulline malate approach, while others may choose an advanced stack like Mother Bucker for longer or more demanding sessions. Start with Bucked Up’s pure L-citrulline or citrulline malate options to experience steady nitric oxide support in your next training block.

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