THE SHORT ANSWER
Your body makes nitric oxide two ways. One route turns the amino acid arginine into nitric oxide and needs oxygen to do it; citrulline feeds that route because your kidneys convert it into arginine. The other route turns dietary nitrate, the compound beets are known for, into nitrite and then nitric oxide, and it works best when oxygen is low, like late in a hard interval. Amino acids act within about 30 to 60 minutes; nitrate takes 2 to 3 hours to peak.
KEY TAKEAWAYS
- Citrulline usually raises blood arginine more reliably than arginine itself.
- Beet nitrate needs your mouth bacteria to work. Skip antibacterial mouthwash on beet days.
- Research doses for nitrate and citrulline are larger than most capsules. Food and timing still matter.
- For evening sessions, a stim-free stack protects your sleep better than a caffeinated pre-workout.
Two ways your body makes nitric oxide
Nitric oxide is a signaling gas. Among other jobs, it tells the smooth muscle around your blood vessels to relax, which supports normal blood flow to working muscle. Pre-workout labels love the word. Very few explain that there are two separate production lines, and they behave differently under load.
Route one: arginine and oxygen
The lining of your blood vessels uses an enzyme called eNOS to turn L-arginine into nitric oxide. It needs oxygen as a raw material. Here is the catch with arginine supplements: a large share of oral arginine gets broken down in your gut and liver before it reaches circulation. L-citrulline mostly skips that step. Your kidneys convert it into arginine, which is why citrulline tends to raise blood arginine more reliably than arginine alone.
Route two: nitrate from food
Beets, spinach, arugula and celery are rich in inorganic nitrate. After you eat them, nitrate is concentrated in your saliva, bacteria on your tongue convert it to nitrite, and nitrite is reduced to nitric oxide in blood and tissue. That last step speeds up when oxygen is low and the muscle is more acidic. In plain terms, the nitrate route keeps working in the ugly part of a session, the final rounds and the last reps of an interval.
What the research shows, honestly
Dietary nitrate has a solid research base in endurance work. A review by Andrew Jones in Sports Medicine described improvements in exercise economy and time to exhaustion in many studies, with the clearest results in recreational athletes and smaller effects in highly trained ones. Most of those studies used concentrated beet juice providing roughly 6 to 8 mmol of nitrate, taken about 2 to 3 hours before exercise.
Citrulline has a smaller but interesting base. In one double-blind crossover study, trained men took 2.4 g of L-citrulline a day for seven days and finished a 4 km cycling time trial faster than on placebo. Results across studies are mixed, and doses vary widely.
Why tell you this on a store blog? Because it sets expectations. Our capsules and powder are daily-use formulas, not the high doses from lab studies. They fit a routine. Nitrate-rich meals, good sleep and smart pacing still do a lot of the heavy lifting.
Three TitanFuel options, side by side
| L-Citrulline & L-Arginine Stack | Beetroot Powder | Nitric Shock Pre-Workout | |
|---|---|---|---|
| Serving | 2 capsules | 1 scoop | 1 scoop |
| Key ingredients | 400 mg L-citrulline DL-malate, 350 mg L-arginine HCl, 50 mg L-arginine AKG | 1,375 mg beet root powder, 1,000 mg hibiscus flower, 500 mg apple juice powder | 1,500 mg L-arginine AKG, 1,500 mg dicreatine malate, 750 mg beta-alanine, 550 mg energy matrix |
| Caffeine | None | None | 175 mg |
| Best timing | 30 to 45 min before training | 60 to 90 min before training | 30 min before training |
| Good fit | Evening lifting, stim-free days | Runs, rucks, rounds | Morning and early afternoon sessions |
Nitric Shock is a full pre-workout. The label says to start with one scoop to check tolerance and never go past two scoops a day, which would be 350 mg of caffeine. The citrulline stack and Beetroot Powder are both caffeine free, so they work as a stim-free pair.
Timing that matches each route
Because the two routes run on different clocks, stacking them at the same moment is the most common mistake. Plasma nitrite rises over a couple of hours after a nitrate dose. Amino acids and caffeine peak much sooner. Plug your session start into the timer to get a countdown.
INTERACTIVE
Pre-training timing planner
Enter when your session starts.
- Full meal window: 1:30 p.m. to 3:30 p.m.
- Small carb snack (if needed): 4:30 p.m. to 5:00 p.m.
- Pre-workout per label: about 5:00 p.m.
- Start: 5:30 p.m.
Training late? A stim-free option may protect your sleep.
Pre-workout timing follows a typical label (about 30 minutes before). Always check your product label.
- 60 to 90 minutes out: beetroot powder in cold water, or a nitrate-rich meal such as a spinach and arugula salad.
- 30 to 45 minutes out: two capsules of the citrulline stack, or one scoop of Nitric Shock on a morning session.
- During: water, plus electrolytes if the session runs long and hot.
Caffeine or stim-free?
Caffeine is one of the best-studied ergogenic aids. The ISSN position stand puts the effective range at about 3 to 6 mg per kg of body weight (about 1.4 to 2.7 mg per lb). For a 180 lb (82 kg) athlete, that is roughly 245 to 490 mg, so one 175 mg scoop of Nitric Shock sits below the bottom of that range on purpose. You can add coffee if you tolerate it, but count every source.
The FDA cites 400 mg a day as an amount not generally associated with negative effects in healthy adults. Caffeine also lingers for hours. If you train after about 3 p.m., a stim-free combination of beetroot and the citrulline stack is the sleep-friendly choice. Our pre-workout timing guide walks through the cutoff math.
MYTH OR FACT
Nitric oxide myths, checked
Tap a myth to see the facts.
MYTHMore arginine means more nitric oxide.
FACTMuch of oral arginine is broken down before it reaches circulation. Citrulline usually raises blood arginine more reliably.
MYTHBeetroot works the minute you drink it.
FACTNitrate needs time to be converted. Plasma nitrite rises over roughly 2 to 3 hours.
MYTHA bigger pump means a better workout.
FACTPump is a feeling. Training quality, load and recovery decide progress.
MYTHStim-free means it does nothing.
FACTThe nitrate and citrulline routes are independent of caffeine. They just do not give you a buzz.
Build your stack by session type
- Morning strength or sprint day: Nitric Shock, one scoop, 30 minutes out. Water during.
- Evening lifting: citrulline stack 30 to 45 minutes out. No caffeine after mid-afternoon.
- Long run, ruck or sparring rounds: beetroot powder 60 to 90 minutes out, citrulline stack 30 to 45 minutes out, electrolytes during.
- Easy day: nothing. Save the pre-workout for sessions that need it.
Before your next hard session
0/5If you are building an engine for the Build Endurance mission or getting ready for timed runs at Level 4, start with the beetroot and citrulline pair on your two hardest sessions of the week and keep the rest simple.
Runners can find study doses, timing before long runs and race-day tips in our guide to beetroot for running.
FAQ
Is L-citrulline better than L-arginine?
For raising blood arginine, citrulline is usually more reliable, because much oral arginine is broken down in the gut and liver. Our stack combines both: 400 mg of L-citrulline DL-malate with 400 mg of arginine from two forms.
When should I take beetroot powder before a workout?
About 60 to 90 minutes before training. Nitrate has to be converted to nitrite first, and plasma nitrite rises over roughly 2 to 3 hours after a dose.
Can I take the citrulline stack and beetroot powder together?
Yes. Both are caffeine free. Take beetroot first, 60 to 90 minutes out, and the capsules 30 to 45 minutes out, so each peaks closer to your session.
How much caffeine is in Nitric Shock?
175 mg per scoop. The label says to start with one scoop and never exceed two scoops a day. Count coffee, tea and energy drinks toward the 400 mg daily amount the FDA cites for healthy adults.
Why does Beetroot Powder contain hibiscus?
Each scoop pairs 1,375 mg of beet root powder with 1,000 mg of hibiscus flower and 500 mg of apple juice powder. Hibiscus brings a tart taste and its own plant compounds, and the blend is sweetened with stevia.
IF YOU WANT A HAND
Fuel that fits this plan
Food and habits come first. If a supplement makes your routine easier, these are the ones that match this article.
SOURCES
- Jones AM. Dietary nitrate supplementation and exercise performance (2014)
- Suzuki T et al. Oral L-citrulline supplementation enhances cycling time trial performance in trained men (2016)
- Govoni M et al. Plasma nitrite rise after a nitrate load is attenuated by antibacterial mouthwash (2008)
- Guest NS et al. ISSN position stand: caffeine and exercise performance (2021)
- FDA: Spilling the Beans, how much caffeine is too much?
This article is for general education and is not medical advice. Talk to your doctor before starting a supplement, especially if you have a health condition, take medication, are pregnant or are under 18. Results vary from person to person.
