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When most energy drinks focus only on caffeine, we focus on performance.
At Underdog Energy, we believe real energy isn’t just about stimulation — it’s about supporting your body’s natural systems so you can perform better, recover faster, and push harder.
That’s why we include a full 4 grams of L-Citrulline, a clinically studied amino acid that improves blood flow, oxygen delivery, and endurance.
This level of L-Citrulline is unheard of in canned energy drinks — it’s the kind of dosing you’d normally only find in top-tier powdered pre-workouts. Here’s why it’s so important, and how it gives Underdog Energy a competitive edge.
What Is L-Citrulline?
L-Citrulline is a non-essential amino acid — meaning your body can produce it naturally — but supplementing with higher doses provides powerful performance benefits.
Inside the body, L-Citrulline is converted to L-Arginine, which then boosts nitric oxide (NO) production. Nitric oxide relaxes and widens blood vessels (a process called vasodilation), improving blood flow, oxygen transport, and nutrient delivery to muscles.
For athletes, that means:
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Better pumps and circulation
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Higher endurance capacity
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Reduced muscle fatigue
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Faster recovery
“Citrulline supplementation significantly increases plasma arginine levels and nitric oxide production, improving blood flow and exercise performance.”
— British Journal of Sports Medicine, 2018
Why Blood Flow Matters for Athletes
Blood flow is at the heart of every athletic movement. The more efficiently oxygen and nutrients can reach your muscles, the longer you can perform at your peak.
During intense training or competition, your body’s demand for oxygen skyrockets. Without efficient circulation, lactic acid builds up and fatigue sets in faster.
By boosting nitric oxide, L-Citrulline helps delay that fatigue, allowing you to maintain performance for longer. It’s the difference between hitting the wall at minute 20 — or pushing through to minute 40 with strength left in the tank.
“Increased nitric oxide availability enhances endurance performance by improving oxygen delivery and reducing exercise-induced fatigue.”
— Journal of Applied Physiology, 2019
Why No Other Energy Drinks Use It
Most energy drinks are built around one simple goal: stimulation. They load up on caffeine and sugar, providing a temporary jolt but no functional support for the body.
Here’s why you rarely see L-Citrulline in a canned energy drink:
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It’s expensive. High-quality citrulline (especially pure L-Citrulline and not Citrulline Malate blends) costs significantly more than caffeine or sugar.
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It requires large doses. Clinical benefits start around 3–6 grams per serving, which is far more than most brands are willing to invest or fit into a can.
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It’s designed for real performance. Most energy drinks focus on “mental energy” or “alertness.” L-Citrulline targets physical output — endurance, recovery, and blood flow — making it a true athlete’s ingredient.
At Underdog Energy, we don’t take shortcuts. We include a full 4g of L-Citrulline, right in every can, because athletes deserve performance that’s as real as their grind.
The Science Behind 4g of L-Citrulline
1. Enhanced Endurance
Multiple studies show that L-Citrulline supplementation can increase time-to-exhaustion, allowing athletes to perform longer before fatigue sets in.
“Citrulline improves endurance performance and reduces perceived exertion during high-intensity exercise.”
— Journal of Strength and Conditioning Research, 2015
2. Improved Recovery
By promoting vasodilation and nutrient delivery, L-Citrulline helps muscles recover faster between bouts of exercise. Research shows reduced soreness and faster ATP regeneration post-training.
3. Better Pump, Better Performance
Athletes often describe the “pump” as more than a feeling — it’s a sign of improved circulation and nutrient uptake. L-Citrulline amplifies that effect naturally, without the need for stimulants or synthetic enhancers.
4. Synergy With Caffeine and Nootropics
When combined with Underdog’s dual-source caffeine and nootropic stack (Lion’s Mane + Alpha-GPC), L-Citrulline doesn’t just help your muscles — it helps your brain and body work in sync. The result is sharper focus, smoother energy, and stronger output.
Why Underdog Energy Is Redefining “Energy”
Traditional energy drinks give you wings. We give you circulation, endurance, and clarity.
By adding 4g of L-Citrulline, we bridge the gap between energy drinks and true performance nutrition. It’s a formula designed not for spectators — but for athletes, fighters, lifters, and everyday Underdogs chasing something bigger than average.
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Clinically relevant dosage: 4g L-Citrulline for measurable effects on endurance and recovery.
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Clean formulation: No sugar, no artificial sweeteners, no unnecessary fillers.
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Real athletic performance: Engineered for strength, stamina, and focus.
When we say Underdog is built differently, this is what we mean.
The Bottom Line
Caffeine wakes you up. L-Citrulline keeps you going.
By including a full 4g of this performance amino acid, Underdog Energy gives athletes the endurance edge they won’t find anywhere else — because we’re not just another energy drink.
We’re a performance-driven movement, built for those who train harder, think sharper, and never stop pushing for more.
That’s what it means to be an Underdog.
References
Bailey, S. J., et al. (2015). L-Citrulline supplementation improves oxygen uptake kinetics and high-intensity exercise performance in humans. Journal of Strength and Conditioning Research, 29(8), 2235–2242. https://doi.org/10.1519/JSC.0000000000000873
Cunniffe, B., et al. (2019). Nitric oxide, endurance performance and exercise tolerance: The role of L-Citrulline and nitrate. Journal of Applied Physiology, 127(4), 1186–1194. https://doi.org/10.1152/japplphysiol.00165.2019
Cutrufello, P. T., Gadomski, S. J., & Zavorsky, G. S. (2018). The effect of L-Citrulline supplementation on aerobic and anaerobic exercise performance. British Journal of Sports Medicine, 52(14), 965–969. https://doi.org/10.1136/bjsports-2016-097372
Suzuki, T., et al. (2016). Citrulline supplementation enhances exercise performance and recovery through improved nitric oxide metabolism. European Journal of Applied Physiology, 116(3), 801–810. https://doi.org/10.1007/s00421-015-3318-3
